2BTEN-B1Subtle Voicebuds

Skywalk Inc. 2.911 (d)(7)USA Agent v1.5 Section 2.911(d)(7) USA Agent for Service of Process Company name: Skywalk Inc. Address: 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, United States FCC ID: 2BTEN-B1 2.911(d)(7) USA Designated Agent for Service of Process We, Skywalk Inc. (“the applicant”) designate Skywalk Inc. NOTE1 for the purpose of accepting service of process on behalf of the applicant. Applicant consent: We acknowledge our consent to accept service of process in the United States for matters related to the applicable equipment, and at the physical U.S. address and email address of the designated agent and acknowledge our acceptance of our obligation to maintain an agent for service of process in the United States for no less than one year after either we the grantee have permanently terminated all marketing and importation of the applicable equipment within the U.S., or at the conclusion of any Commission-related administrative or judicial proceeding involving the equipment, whichever is later. Agent obligation: We acknowledge our obligation to accept service of process in the United States for matters related to the applicable equipment at our physical U.S. address and email address for no less than one year after either the grantee has permanently terminated all marketing and importation of the applicable equipment within the U.S., or at the conclusion of any Commission-related administrative or judicial proceeding involving the equipment, whichever is later. USA Agent & Applicant Company name: Skywalk Inc. USA Address: 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, United States FRN Number: 0037692423 Contact Name: Tyler Chen Telephone No: (760) 505-9913 Email: [email protected] Signature: Title: CEO Date: Mar. 04, 2026 NOTE 1: An applicant located in the United States may designate itself as the agent for service of process. Reference; Federal Register document 2022-28263 published on 02/06/23 Skywalk Inc. 2.911 (d)(7)USA Agent v1.5 https://www.federalregister.gov/documents/2023/02/06/2022-28263/protecting-against-nation al-security-threats-to-the-communications-supply-chain-through-the

Skywalk Inc. 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, United States Attestation Statements Not Covered Entity Applicant & Not Covered Equipment To: Federal Communications Commission Date: Mar. 04, 2026 7435 Oakland Mills Road, Columbia, MD 21046, USA Ref: Information Required by Section 2.911(d)(5)(i) & (ii) FCC ID: 2BTEN-B1 Skywalk Inc. (“the applicant”) certifies that, as of the date of the filing of the application, the applicant is not identified on the Covered List, established pursuant to § 1.50002 of reference chapter, as an entity producing “covered” communication equipment. The equipment for which authorization is sought is not “covered” telecommunications equipment and video surveillance equipment produced by entities identified on the Commission’s Covered List that prohibited from receiving an equipment authorization pursuant to section § 2.903 of the FCC rules. Sincerely yours, Applicant Signature Printed Name: Tyler Chen Title: CEO Address: 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, United States Tel.: (760) 505-9913 Email: [email protected]

Skywalk Inc. 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, United States 1 | Page Attestation Statements To: Federal Communications Commission Date: Mar. 04, 2026 7435 Oakland Mills Road, Columbia, MD 21046, USA Subject: Attestation of Compliance with FCC Covered List Software Requirements FCC ID: 2BTEN-B1 Product Name: Subtle Voicebuds This letter serves as an attestation that the equipment identified above ☐ is / ☒ is not (select one) "covered" software as defined under the Federal Communications Commission (FCC) Covered List requirements, as outlined in FCC 22-84 and KDB 986446. Specifically, the undersigned certifies that the equipment for which authorization is sought: 1. Does not contain cybersecurity or anti-virus software produced or provided by Kaspersky Lab, Inc. or any of its successors, assignees, parents, subsidiaries, affiliates, or any entity that has rebranded or relabeled software produced by the aforementioned entities. 2. Does not have the capability to store, run, or deliver any software identified on the FCC Covered List, including but not limited to cybersecurity and anti-virus software. To support this attestation, the appendix evaluation documentation has been prepared and is included in the certification filing. This attestation is based on a thorough evaluation of the device's design, functionality, and software environment. The undersigned affirms that the information provided is accurate and complete to the best of their knowledge. Sincerely yours, Applicant Signature Printed Name: Tyler Chen Title: CEO Address: 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, United States Tel.: (760) 505-9913 Email: [email protected] Skywalk Inc. 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, United States 2 | Page Evaluation regarding to the Covered List Software: Compliance Methodology Evaluation Process Results Device is Inherently compliant ☒ The Chipset(s) used does not have the capability to run the Cybersecurity or anti-virus software. Compliance ☐ The Memory used does not have the capability to run the Cybersecurity or anti-virus software. Compliance ☐ There is storage capacity limitation for store or install the Cybersecurity or anti-virus software. Compliance ☐ Operating system used is limited to run, install or deliver the Cybersecurity or anti-virus software. Compliance Device is not Inherently compliant ☐ Evaluation Based on Software Bill of Materials (SBoM) See attached “SBoM“ Note:The SBoM content is limited to the scope of covered list software (e.g. antivirus and cybersecurity software). ☐ Evaluation Based on Scan for Software on the device ☐ Evaluation Based on Filesystem scan ☐ Evaluation Based on Running software check SBOM (Software Bill of Materials) [For Device is not Inherent compliance] Section Component Name Version Supplier 1 2 3

Skywalk Inc. 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, USA Mar. 04, 2026 Office of Engineering Technology Federal Communications Commission 7435 Oakland Mills Road Columbia, MD 21046 USA Subject: Explanation of differences between product types FCC ID: 2BTEN-B1 Models: AC11, AC1B1, AC1W1 To Whom It May Concern: We, The Skywalk Inc. hereby declare that the model : AC11 is identical with the model : AC1B1, AC1W1, except the model name and color. Sincerely, Skywalk Inc. Signature: [Tyler Chen, CEO]

Skywalk Inc. 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, United States Office of Engineering Technology Federal Communications Commission 7435 Oakland Mills Road Columbia, MD 21046 USA Date: Mar. 04, 2026 Subject; Request for Confidentiality FCC ID: 2BTEN-B1 To Whom It May Concern, Pursuant to the provisions of the Commission’s rules Title 47 Sections §0.457 and §0.459, we are requesting the Commission to withhold the following attachment(s) as confidential documents from public disclosure indefinitely. These documents contain detailed system and equipment descriptions and are considered as proprietary information in operation of the equipment. The public disclosure of these documents might be harmful to our company and would give competitors an unfair advantage in the market. Schematic Diagram Block Diagram Operational Description In additional to above mentioned documents, in order to comply with the marketing regulations in Title 47 CFR §2.803 and the importation rules in Title 47 CFR §2.1204, while ensuring that business sensitive information remains confidential until the actual marketing of newly authorized devices, we request Short Term Confidentiality of the following attachment(s); External Photos Test Setup Photos Internal Photos User Manual For 45 days, pursuant to Public Notice DA 04-1705. OR For 180 days pursuant to KDB 726920 D01. It is our understanding that all measurement test reports, FCC ID label format and correspondence during the certification review process cannot be granted as confidential documents and this information will be available for public review once the grant of equipment authorization is issued. Sincerely, Signature: Name: Tyler Chen Title: CEO

Skywalk Inc. 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, USA Mar. 04, 2026 Federal Communications Commission Authorization and Evaluation Division 7435 Oakland Mills Road Columbia, MD 21046 Subject: Agent Authorization for FCC ID: 2BTEN-B1 I, the undersigned, hereby authorize (Attestation of Global Compliance (Shenzhen) Co., Ltd) to act on our behalf in all matters relating to this application for equipment certification. Any act carried out by (Attestation of Global Compliance (Shenzhen) Co., Ltd) shall have the same effect as our own and I acknowledge that all responsibility for complying with the terms and conditions of certification, as specified by DERYCOM CERTIFICATION SERVICES, INC., still resides with Skywalk Inc. We certify that we are not subject to a denial of federal benefits that includes FCC benefits pursuant to Section 5301 of the Anti-Drug Abuse Act of 1988, 21 U.S.C. §862, and that no party to the application, as defined in 47 CFR §1.2002(b), is subject to a denial of federal benefits that includes FCC benefits pursuant to that section. Sincerely, Full name of contact person listed on FCC’s website: Tyler Chen Title: CEO Tel: (760) 505-9913 Email: [email protected]

FCC ID Label Location The product does not have enough space to place the label, and FCC ID is reflected in the user manual and package. User manual as below: Package as below:

Page 1 of 10 RF Exposure Report Report No.: AGC01082260106FH01 FCC ID : 2BTEN-B1 APPLICATION PURPOSE : Original Equipment PRODUCT DESIGNATION : Subtle Voicebuds BRAND NAME : Subtle MODEL NAME : AC11, AC1B1, AC1W1 APPLICANT : Skywalk Inc. DATE OF ISSUE : Mar. 04, 2026 STANDARD(S) : FCC Part 2 Subpart J §2.1093 FCC KDB 447498 D01 V06 REPORT VERSION : V1.0 Attestation of Global Compliance (Shenzhen) Co., Ltd Report No.: AGC01082260106FH01 Page 2 of 10 Report Revise Record Report Version Revise Time Issued Date Valid Version Notes V1.0 / Mar. 04, 2026 Valid Initial Release Report No.: AGC01082260106FH01 Page 3 of 10 Table of Contents 1. General Information ........................................................................................................................................ 4 2. Product Information ........................................................................................................................................ 5 2.1 Product Technical Description ................................................................................................................... 5 3. Test Environment ............................................................................................................................................ 6 3.1 Address Of The Test Laboratory ............................................................................................................... 6 3.2 Test Facility ................................................................................................................................................ 6 3.3 Environmental Conditions ......................................................................................................................... 7 4. Portable Device Evaluation Method and Limit ............................................................................................. 8 5. Measurement Results ..................................................................................................................................... 9 6. Measurement Evaluation ................................................................................................................................ 9 Report No.: AGC01082260106FH01 Page 4 of 10 1. General Information Applicant Skywalk Inc. Address 855 El Camino Real, Suite 13A - 230, Palo Alto, CA 94301, USA Manufacturer GuangZhou U&I Technology Company Limited Address 4th Floor, 15th Building, Vtrek Innovation Industrial Park, No. 644, Shibei Road, Panyu District, Guangzhou, China Factory GuangZhou U&I Technology Company Limited Address 4th Floor, 15th Building, Vtrek Innovation Industrial Park, No. 644, Shibei Road, Panyu District, Guangzhou, China Product Designation Subtle Voicebuds Brand Name Subtle Test Model AC11 Series Model(s) AC1B1, AC1W1 Difference Description All the same except for the model name and color. Date of receipt of test item Jan. 29, 2026 Date of Test Jan. 29, 2026 to Mar. 04, 2026 Deviation from Standard No any deviation from the test method Condition of Test Sample Normal Test Result Pass Test Report Form No AGCER-FCC-RF Exposure-V1 Note: The test results of this report relate only to the tested sample identified in this report. Prepared By Thea Huang (Project Engineer) Mar. 04, 2026 Reviewed By Bibo Zhang (Reviewer) Mar. 04, 2026 Approved By Angela Li (Authorized Officer) Mar. 04, 2026 Report No.: AGC01082260106FH01 Page 5 of 10 2. Product Information 2.1 Product Technical Description Frequency Band (Operating) Bluetooth: 2.402GHz ~ 2.480GHz Other: Hardware Version V02-03 Software Version V1.4.4.11 Modulation Type BR GFSK, EDR π /4-DQPSK, 8DPSK BLE GFSK 1Mbps GFSK 2Mbps Maximum Transmitter Power BR&EDR: -4.334dBm BLE GFSK 1Mbps: -0.030dBm Device Category Portable (<20cm separation) Mobile (>20cm separation) Others: Antenna Diversity Single antenna Multiple antennas Tx diversity Rx diversity Tx/Rx diversity Antenna Designation FPC Antenna Antenna Gain -1.66dBi Minimum Assessment Distance 5mm Evaluation Applied MPE Evaluation SAR Evaluation Report No.: AGC01082260106FH01 Page 6 of 10 3. Test Environment 3.1 Address Of The Test Laboratory Laboratory: Attestation of Global Compliance (Shenzhen) Co., Ltd. Address: 1-2/F, Building 19, Junfeng Industrial Park, Chongqing Road, Heping Community, Fuhai Street, Bao'an District, Shenzhen, Guangdong, China 3.2 Test Facility The test facility is recognized, certified, or accredited by the following organizations: CNAS-Lab Code: L5488 Attestation of Global Compliance (Shenzhen) Co., Ltd. has been assessed and proved to follow CNAS-CL01 Accreditation Criteria for Testing and Calibration Laboratories (identical to ISO/IEC17025: 2017 General Requirements for the Competence of Testing and Calibration Laboratories.) A2LA-Lab Cert. No.: 5054.02 Attestation of Global Compliance (Shenzhen) Co., Ltd. EMC Laboratory has been accredited by A2LA for technical competence in the field of electrical testing, and proved to follow ISO/IEC 17025: 2017 General Requirements for the Competence of Testing and Calibration Laboratories and any additional program requirements in the identified field of testing. FCC-Registration No.: 975832 Attestation of Global Compliance (Shenzhen) Co., Ltd. EMC Laboratory has been registered and fully described in a report filed with the FCC (Federal Communications Commission). The acceptance letter from the FCC is maintained in our files with Registration 975832. IC-Registration No.: 24842(CAB identifier: CN0063) Attestation of Global Compliance (Shenzhen) Co., Ltd. EMC Laboratory has been registered and fully described in a report filed with the Certification and Engineering Bureau of Industry Canada. The acceptance letter from the IC is maintained in our files with Registration 24842. Report No.: AGC01082260106FH01 Page 7 of 10 3.3 Environmental Conditions NORMAL CONDITIONS Temperature range (°C) 15 - 35 Relative humidity range 20 % - 75 % Pressure range (kPa) 86 - 106 Power supply DC 3.85V by batte…

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customer Name Guangzhou Youwo Technology Co., Ltd. Customer project Name BS588H2M Heyix un project Name BS588H2M customer P/N Heyixun P/ N HYX008-588-V4.1 Band 2400-2500MHz Antenna type FPC Designer Information RF Engineer Feng Xiaoheng EE Engineer Feng Xiaoheng ME Engineer Xu Liang Heyixun Approval customer Approval p re pa red checked BY Approval BY checked BY Approval BY signature Xiao Jingxian Date 2025-12-25 change Log vers ion change Descriptionperson in charge Approval BY Date Shenzhen Heyixun Technology Co., LTD SPECIFICATION FOR APPROVAL address： 1903-1905, Bu i ld ing 2, J iufang Square, T ie za i Road, Gong le Commun ity, X i x iang Street, Bao ' an D istr ict, Shenzhen 1 Guangzhou Youwo Techno logy Co., Ltd. catalogue No. Item Page No. 1 Drawing or Product Image 3 2 Dimens ions Test Report 4 3 RF Performance Test Report 5-8 4 Rel iabi l ity Test Report 9 5 PACK ING CRITERION 10 6 Environmental requ irements 10 7 Install Wizard or Other 11 Shenzhen Heyixun Technology Co., LTD address： 1903-1905, Bu i ld ing 2, J iufang Square, T ie za i Road, Gong le Commun ity, X i x iang Street, Bao 'an D istr ict, Shenzhen 2 Shenzhen Hey i Xun Technology Co., Ltd. Drawing or Product Image Address: No.2 Building, Jiu Fang Plaza, Gong Le Community, Xixiang Sub-district, Bao'an District, Shenhen City 1903- 1905 TEL： 0755- 23591525 FAX：0755-23591525 3 Customer Name Guangzhou Youwo Technology Co., Ltd. Customer P/N HeY ixun P/N HYX008-588-V4.1 Test Date 2025-12-25 Samp le Qty. 3 Inspector Xiao Jingxian D imens ion No. Standard Samp le 1Samp le 2Samp le 3 Pass/NG ①length 15.30±0.2mm 15.31mm15.30mm15.30mm Pass ②width 3.01±0.2mm3.01mm3.00mm3.02mm Pass ③Thickne ss 0.2±0.05mm0.20mm0.20mm0.20mm Pass Conclus ion PASS Inspector & Date Xiao Jingx 25 ian 2025-12- Approva l &D ate Shenzhen Hey i Xun Technology Co., Ltd. Samp le Dimens ions Test Report Address: No.2 Building, Jiu Fang Plaza, Gong Le Community, Xixiang Sub-district, Bao'an District, Shenhen City 1903- 1905 TEL： 0755- 23591525 FAX：0755-23591525 4 customer Name Guangzhou Youwo Technology Co., Ltd. project Name BS588H2M Heyixun P/ N HYX008-588-V4.1 Band 2400-2500MHZ Test Date 2025-12-25 Inspector Xiao Jingxian Antenna Test Equ ipment Introduct ion Test of antenna input character ist ics us ing Agilent E5071c andAgilent5071c vector network ana lyzer ; The rad iat ion pattern of the antenna are tested us ing the ETS star lab 3D near f ie ld Anecho ic Chamber, and the instrument is used to ag i lent8960 E5515 and Ag i lent E4438C. The test coord inates of the darkroom are as fo llows : Shenzhen Heyixun Technology Co., LTD RF Performance Test Report address： 1903-1905, Bu i ld ing 2, J iufang Square, T ie za i Road, Gong le Commun ity, X i x iang Street, Bao 'an D istr ict, Shenzhen 5 Shenzhen Heyixun Technology Co., LTD address： 1903-1905, Bu i ld ing 2, J iufang Square, T ie za i Road, Gong le Commun ity, X i x iang Street, Bao 'an D istr ict, Shenzhen 7 Shenzhen Heyixun Technology Co., LTD address： 1903-1905, Bu i ld ing 2, J iufang Square, T ie za i Road, Gong le Commun ity, X i x iang Street, Bao 'an D istr ict, Shenzhen 7 customer Name Guangzhou Youwo Technology Co., Ltd. customer P/N Heyixun P/ N HYX008-588-V4.1 Test Date 2025-12-25 samp le Qty. 3 Inspector Xiao Jingxian Test Item Requireme t e st i n g equipment samp le 1 samp le 2 samp le 3 PASS/ NG High temperature storage The test was performed after 24 hours of exposure at +85°C and 2 hours of recovery Constant temperature and humidity chamber OKOKOK Pass Cryogenic storage The test was performed after 24 hours of exposure at -40°C and 2 hours of recovery Constant temperature and humidity chamber OKOKOK Pass High temperature operation Operates at +60°C for 24 hours Constant temperature and humidity chamber OKOKOK Pass Operates at low temperatures It works on power for 24H at -20°C Constant temperature and humidity chamber OKOKOK Pass Salt spray test (5 Shi 0.5)*Sodium chloride, pH value is 6.5~7.2, and the temperature of the exper imental chamber is (35 ±2) °C ☑24H □48H Salt spray testing machine OKOKOK Pass Connector r ivet ing pull-out force 1.13 Wire size ≥10N 0.81 Wire size ≥8N RG174 ≥60N RG178 ≥50N Push-pull force gauge //// Conclus ion Pass Inspector & Date Xiao Jingxian 2025-12-25 Approva l &D ate Shenzhen Heyixun Technology Co., LTD Rel iabi l ity Test Report address： 1903-1905, Bu i ld ing 2, J iufang Square, T ie za i Road, Gong le Commun ity, X i x iang Street, Bao 'an D istr ict, Shenzhen 9 2 、 Large PE bag packag ing (fu ll version/sing le 90pcs) (subject to actual packag ing) 3 、 Seal the box, and affix our company's product ion label and ROHS label to the outer box. (Subject to actual packag ing Shenzhen Hey i Xun Technology Co., Ltd. PACK ING CR ITER ION 1、Sing le product (subject to actual packag ing) Address: No.2 Building, Jiu Fang Plaza, Gong Le Community, Xixiang Sub-district, Bao'an District, Shenhen City 1903- 1905 TEL： 0755- 23591525 FAX：0755-23591525 6 Install Wizard or Other Installation Process: Take the 1PCS product, tear off the release paper on the back of the FPC by hand, and then align the position of the FPC positioning hole with the positioning hole position of the shell (positioning rib or positioning line), and attach it to the shell flatly, the specific position is shown in the following figure: Precautions during the installation process: ☑After attach ing the antenna, ensure that the FPC is fully attached to the housing； ☑The pos it ion ing hole is al igned with the positioning post pos it ion of the hous ing； ☑The edge of the FPC is against the edge of the case； □Antenna with TerminalsWhen snapping the terminals to the PCBA end of the motherboard, first snap the terminals and then vert ically； □When d isassemb ling the antenna terminals, it is necessary to use a tool (such as a special crowbar) to the terminals vert ically, and do not d irect ly pu ll the wire to d isassemble them。 address： 1903-1905, Bu i ld ing 2, J iufang Square, T ie za i Road,…

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Page 1 of 47 FCC Test Report Report No.: AGC01082260106FR02 FCC ID : 2BTEN-B1 APPLICATION PURPOSE : Original Equipment PRODUCT DESIGNATION : Subtle Voicebuds BRAND NAME : Subtle MODEL NAME : AC11, AC1B1, AC1W1 APPLICANT : Skywalk Inc. DATE OF ISSUE : Mar. 04, 2026 STANDARD(S) : FCC Part 15 Subpart C §15.247 REPORT VERSION : V1.0 Attestation Of Global Compliance (Shenzhen) Co., Ltd Report No.: AGC01082260106FR02 Page 2 of 47 Report Revise Record Report Version Revise Time Issued Date Valid Version Notes V1.0 / Mar. 04, 2026 Valid Initial Release Report No.: AGC01082260106FR02 Page 3 of 47 Table of Contents 1. General Information ........................................................................................................................................ 5 2. Product Information ........................................................................................................................................ 6 2.1 Product Technical Description ................................................................................................................... 6 2.2 Test Frequency List ................................................................................................................................... 6 2.3 Related Submittal(S) / Grant (S) ............................................................................................................... 7 2.4 Test Methodology ...................................................................................................................................... 7 2.5 Special Accessories .................................................................................................................................. 7 2.6 Equipment Modifications ........................................................................................................................... 7 2.7 Antenna Requirement................................................................................................................................ 7 3. Test Environment ............................................................................................................................................ 8 3.1 Address of the Test Laboratory ................................................................................................................. 8 3.2 Test Facility ................................................................................................................................................ 8 3.3 Environmental Conditions ......................................................................................................................... 9 3.4 Measurement Uncertainty ......................................................................................................................... 9 3.5 List of Equipment Use ............................................................................................................................. 10 4. System Test Configuration ........................................................................................................................... 12 4.1 EUT Configuration ................................................................................................................................... 12 4.2 EUT Exercise ........................................................................................................................................... 12 4.3 Configuration of Tested System .............................................................................................................. 12 4.4 Equipment Used In Tested System ........................................................................................................ 12 4.5 Summary of Test Results ........................................................................................................................ 13 5. Description of Test Modes ........................................................................................................................... 14 6. Duty Cycle Measurement ............................................................................................................................. 15 7. RF Output Power Measurement .................................................................................................................. 16 7.1 Provisions Applicable .............................................................................................................................. 16 7.2 Measurement Procedure ......................................................................................................................... 16 7.3 Measurement Setup (Block Diagram of Configuration) .......................................................................... 16 7.4 Measurement Result ............................................................................................................................... 16 8. 6dB Bandwidth Measurement ...................................................................................................................... 19 8.1 Provisions Applicable .............................................................................................................................. 19 8.2 Measurement Procedure ......................................................................................................................... 19 8.3 Measurement Setup (Block Diagram of Configuration) .......................................................................... 19 8.4 Measurement Results ............................................................................................................................. 20 9. Power Spectral Density Measurement ........................................................................................................ 24 9.1 Provisions Applicable .............................................................................................................................. 24 9.2 Measurement Proced…

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