2A4WD-ZK502MBluetooth Audio Power Amplifier

(Qingdao Wuzhi Intelligent Technology Co., Ltd.) (September 3, 2024) Eurofins Electrical and Electronic Testing NA, Inc. 914 West Patapsco Avenue Baltimore, MD 21230 RE: Attestation Statements Part 2.911(d)(5)(i) request for (FCC ID: 2A4WD-ZK502M) [Qingdao Wuzhi Intelligent Technology Co., Ltd.] (“the applicant”) certifies that the equipment for which authorization is sought is not “covered” equipment prohibited from receiving an equipment authorization pursuant to section 2.903 of the FCC rules. Sincerely, (Applicant signature) (Applicant printed name) CHENCHEN ZHANG (Qingdao Wuzhi Intelligent Technology Co., Ltd.) (September 3, 2024) Eurofins Electrical and Electronic Testing NA, Inc. 914 West Patapsco Avenue Baltimore, MD 21230 RE: Attestation Statements Part 2.911(d)(5)(ii) request for (FCC ID: 2A4WD-ZK502M) [Qingdao Wuzhi Intelligent Technology Co., Ltd.] (“the applicant”) certifies that, as of the date of the filing of the application, the applicant is not identified on the Covered List as an entity producing “covered” equipment. Sincerely, (Applicant signature) (Applicant printed name) CHENCHEN ZHANG

Attestation Statements (September 3, 2024) TO: Federal Communications Commission Authorization and Evaluation Division 7435 Oakland Mills Road Columbia, MD 21046, USA RE: Attestation Statements Part 2.911(d)(7) request for (FCC ID: 2A4WD-ZK502M ) (Qingdao Wuzhi Intelligent Technology Co., Ltd.), the undersigned, hereby authorize (SOUTH BAY INNOVATION LLC) to act as our designated U.S. agent for service of process, (Qingdao Wuzhi Intelligent Technology Co., Ltd.) accepts to maintain an agent for no less than one year after the grantee has terminated all marketing and importation or the conclusion of any Commission-related proceeding involving the equipment. (SOUTH BAY INNOVATION LLC) accepts the responsibility to act as designated U.S. agent for service of process, provides an agent for no less than one year after the grantee has terminated all marketing and importation or the conclusion of any Commission-related proceeding involving the equipment. Applicant Information： Company name: Qingdao Wuzhi Intelligent Technology Co., Ltd. Contact Name: CHENCHEN ZHANG Address: No. 438, Xiaoxinhe Road, Huangdao District, Qingdao City, Shandong Province, China Telephone No: 13538214502 Email: [email protected] FRN: 0032008856 Signature [CHENCHEN ZHANG] U.S. Agent Information: Company Name: SOUTH BAY INNOVATION LLC Address: 23545 CRENSHAW BLVD STE 106 Torrance, CA 90505 Contact Name: Yueting Zhu Telephone No: 4243769142 Email: [email protected] FRN: 0033401811 Signature [Yueting Zhu]

Qingdao Wuzhi Intelligent Technology Co., Ltd. Model Difference Data：September 3, 2024 Product description: Bluetooth Audio Power Amplifier Model name: ZK-502M, ZK-1002M, ZK-502H, ZK-1001B, ZK-LRC Trade Name: WUZHI AUDIO FCC ID: 2A4WD-ZK502M All the model are the same circuit and RF module, only the name and output audio power are different. Regards Sincerely Client’s signature : Client’s name / title : CHENCHEN ZHANG（General manager） Contact information / address：No. 438, Xiaoxinhe Road, Huangdao District, Qingdao City, Shandong Province, China

Qingdao Wuzhi Intelligent Technology Co., Ltd. (September 3, 2024) Eurofins Electrical and Electronic Testing NA, Inc. 914 West Patapsco Avenue Baltimore, MD 21230 RE: CONFIDENTIALITY REQUEST FOR (Bluetooth Audio Power Amplifier / ZK- 502M, ZK-1002M, ZK-502H, ZK-1001B, ZK-LRC / FCC ID: 2A4WD-ZK502M ) To Whom It May Concern: This letter serves as an official request for confidentiality under sections 0.457 and 0.459 of CFR 47. We have requested that the Exhibits Long-Term Confidentiality Short-Term Confidentiality NOTE 2 ID Label/Location No No Attestation Statement No No External Photos No ☐ Block Diagram ☒ ☐ Schematics ☒ ☐ Test Report No No Test Setup Photos No ☐ User’s Manual ☐ NOTE 1 ☒ Internal Photos ☐ NOTE 1 ☒ Parts List / Tune Up ☐ ☐ RF Exposure Info No No Operational Description ☒ ☐ Cover Letter(s) No No SDR Software / Security Info ☐ No required to be submitted with this application be permanently withheld from public review. Above mentioned document contains detailed system and equipment description are considered as proprietary information in operation of the equipment. The public disclosure of above documents might be harmful to our company and would give competitor an unfair advantage in the market. Please contact me if there is any information you may need. Sincerely, Signature: Name: CHENCHEN ZHANG Title: General manager

Qingdao Wuzhi Intelligent Technology Co., Ltd. (September 3, 2024) Eurofins Electrical and Electronic Testing NA, Inc. 914 West Patapsco Avenue Baltimore, MD 21230 RE: LETTER OF AGENT AUTHORIZATION To Whom It May Concern: We, the undersigned, hereby authorize (Shenzhen CTB Testing Technology Co., Ltd.) to act on our behalf in all matters relating to application for equipment authorization, including the signing of all documents relating to these matters. We also hereby certify that no party to the application authorized hereunder is subject to the denial of benefits, including FCC benefits, pursuant to Section 5301 of the Anti-Drug Abuse Act of 1988, 21 U.S.C.853(a). This agreement expires one year from the current date. Sincerely, Signature: Name: CHENCHEN ZHANG Title: General manager

Shenzhen CTB Testing Technology Co., Ltd. Report Tel: 4008-707-283 Web: http://www.ctb-lab.net Page 1 of 3 Model: ZK-502M External Photos Shenzhen CTB Testing Technology Co., Ltd. Report Tel: 4008-707-283 Web: http://www.ctb-lab.net Page 2 of 3 Shenzhen CTB Testing Technology Co., Ltd. Report Tel: 4008-707-283 Web: http://www.ctb-lab.net Page 3 of 3

FCC ID LABEL: Label Location: FCC ID: 2A4WD-ZK502M Model No.: ZK-502M

Shenzhen CTB Testing Co., Ltd. FCC ID:2A4WD-ZK502M Portable device According to §15.247(e)(i) and §1.1307(b)(1), systems operating under the provisions of this section shall be operated in a manner that ensures that the public is not exposed to radio frequency energy level in excess of the Commission’s guidelines. According to KDB447498 D01 General RF Exposure Guidance V06 The 1-g SAR and 10-g SAR test exclusion thresholds for 100 MHz to 6 GHz at test separation distances ≤ 50 mm are determined by: [(max. power of channel, including tune-up tolerance, mW)/(min. test separation distance, mm)]·[√f(GHZ)] ≤ 3.0 for 1-g SAR and ≤ 7.5 for 10-g extremity SAR, where: • f(GHZ) is the RF channel transmit frequency in GHz • Power and distance are rounded to the nearest mW and mm before calculation • The result is rounded to one decimal place for comparison When the minimum test separation distance is < 5 mm, a distance of 5 mm is applied to determine SAR test exclusion. EDR: Modulation Channel Freq. (GHz) Conduct ed power (dBm) Conducte d power (mW) Tune-up power (dBm) Max tune-up power (dBm) Max tune-up power (mW) Distance (mm) Result calculatio n SAR Exclusion threshold SAR test exclusion 2.402 2.422 1.75 2±1 3.00 2.00 <5 0.61847 3.00 YES 2.441 2.968 1.98 2±1 3.00 2.00 <5 0.62347 3.00 YES 2.480 2.895 1.95 2±1 3.00 2.00 <5 0.62843 3.00 YES 2.402 3.051 2.02 3±1 4.00 2.51 <5 0.77860 3.00 YES 2.441 3.633 2.31 3±1 4.00 2.51 <5 0.78490 3.00 YES 2.480 3.506 2.24 3±1 4.00 2.51 <5 0.79114 3.00 YES GFSK π /4DQPSK Conclusion: For the max result : 0.79114≤ FCC Limit 3.0 for 1g SAR.

TEST REPORT Compiled by: Reviewed by: Approved by: Zhou Kui Arron Liu Bin Mei / Director Note: If there is any objection to the inspection results in this report, please submit a written report to the company within 15 days from the date of receiving the report. The test report is effective only with both signature and specialized stamp. This result(s) shown in this report refer only to the sample(s) tested. Without written approval of Shenzhen CTB Testing Technology Co., Ltd. this report can’t be reproduced except in full. The tested sample(s) and the sample information are provided by the client. “*” indicates the testing items were fulfilled by subcontracted lab. “#” indicates the items are not in CNAS accreditation scope. Product Name: Bluetooth Audio Power Amplifier FCC ID: 2A4WD-ZK502M Trademark: WUZHI AUDIO Model Number: ZK-502M, ZK-1002M, ZK-502H, ZK-1001B, ZK-LRC Prepared For: Qingdao Wuzhi Intelligent Technology Co., Ltd. Address: No. 438, Xiaoxinhe Road, Huangdao District, Qingdao City, Shandong Province, China Manufacturer: Qingdao Wuzhi Intelligent Technology Co., Ltd. Address: No. 438, Xiaoxinhe Road, Huangdao District, Qingdao City, Shandong Province, China Prepared By: Shenzhen CTB Testing Technology Co., Ltd. Address: 1&2/F., Building A, No.26, Xinhe Road, Xinqiao, Xinqiao Street, Bao'an District, Shenzhen, Guangdong, China Sample Received Date: Aug. 23, 2024 Sample tested Date: Aug. 23, 2024 to Aug. 27, 2024 Issue Date: Aug. 27, 2024 Report No.: CTB240827051RF Test Standards FCC CFR Title 47 Part 15 Subpart C Section 15.247 ANSI C63.10:2013 Test Results PASS Remark: This is Bluetooth radio test report. Shenzhen CTB Testing Technology Co., Ltd. Report No.: CTB240827051RF Report Tel: 4008-707-283 Web: http://www.ctb-lab.net Page 2 of 51 TABLE OF CONTENT Test Report Declaration Page 1. VERSION .......................................................................... 4 2. TEST SUMMARY ................................................................... 5 3. MEASUREMENT UNCERTAINTY ..................................................... 6 4. PRODUCT INFORMATION AND TEST SETUP .......................................... 7 4.1 Product Information .................................................................... 7 4.2 Test Setup Configuration ............................................................... 7 4.3 Support Equipment .................................................................... 7 4.4 Channel List .......................................................................... 8 4.5 Test Mode ............................................................................ 8 4.6 Test Environment ...................................................................... 8 5. TEST FACILITY AND TEST INSTRUMENT USED ....................................... 9 5.1 Test Facility ........................................................................... 9 5.2 Test Instrument Used .................................................................. 9 6. AC POWER LINE CONDUCTED EMISSION ............................................ 12 6.1 Block Diagram Of Test Setup .......................................................... 12 6.2 Limit ................................................................................ 12 6.3 Test procedure ....................................................................... 12 6.4 Test Result .......................................................................... 14 7. RADIATED SPURIOUS EMISSION ................................................... 16 7.1 Block Diagram Of Test Setup .......................................................... 16 7.2 Limit ................................................................................ 16 7.3 Test procedure ....................................................................... 17 7.4 Test Result .......................................................................... 18 8. BAND EDGE AND RF COUNDUCTED SPURIOUS EMISSIONS .......................... 27 8.1 Block Diagram Of Test Setup .......................................................... 27 8.2 Limit ................................................................................ 27 8.3 Test procedure ....................................................................... 27 8.4 Test Result .......................................................................... 28 9. COUDUCTED PEAK OUTPUT POWER ............................................... 33 9.1 Block Diagram Of Test Setup .......................................................... 33 9.2 Limit ................................................................................ 33 9.3 Test procedure ....................................................................... 33 9.4 Test Result .......................................................................... 33 10. 20DB OCCUPIED BANDWIDTH...................................................... 36 10.1 Block Diagram Of Test Setup ......................................................... 36 10.2 Limit ............................................................................... 36 10.3 Test procedure ...................................................................... 36 10.4 Test Result ......................................................................... 36 11. CARRIERFREQUENCIES SEPARATION .............................................. 39 11.1 Block Diagram Of Test Setup ......................................................... 39 11.2 Limit ............................................................................... 39 11.3 Test procedure ...................................................................... 39 11.4 Test Result ......................................................................... 39 12. HOPPING CHANNEL NUMBER ...................................................... 42 12.1 Block Diagram Of Test Setup ......................................................... 42 12.2 Limit ...............................................…

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V . S .W . R < 1.4 Polarization Type V ertical & Horizontal Frequenc Range2400 ~ 2500GHz Input Impendence(ohm)50 Ef ficiency (dB) 6 0.2 % 6 0.2 %-3.61.91.2 Maximum Power (dBm)1.7 (XY-plane) Gain (dBi)1.2 (Avg Gain XY-plane) Peak EIRP(dBm)1.2 Tot. Rad. Pwr. (dBm)-1.2 (Input pwr – loss pwr) Product sp ecification Qu ick Reference Date Antenna m odule on the system board Ant. Port Input Pwr. (dBm)0 (Typ. BT class 2 output power) Directivity (dBi)1 (all direction antenna) Minimu m Power (dBm)-4(XY-plane) Avg. Power (dBm)-0.5(XY-plane) All the technical data and information contained herein are subject to change without prior notice Antenna Layout & module on the system board Antenna Gain Ga in Table Unit in dBi @2.44GHz XY-planeXZ-planeYZ-plane Efficiency Peak Avg. Peak Avg. Peak Avg. Module Board -0.51.1-3.0 Return Loss The Environment of Antenna Radiation Pattern 3D radiation pattern diagram XY -planeXZ-planeYZ-plane Manufacturer: Qin gdao Wuzhi Intelligent Technology Co., Ltd. Address: No. 438, Xiaoxinhe Road, Huangdao District, Qingdao City, Shandong Province, China

Shenzhen CTB Testing Technology Co., Ltd. Report Tel: 4008-707-283 Web: http://www.ctb-lab.net Page 1 of 2 Model: ZK-502M Radiated Emission Below 1G Above 1G Shenzhen CTB Testing Technology Co., Ltd. Report Tel: 4008-707-283 Web: http://www.ctb-lab.net Page 2 of 2 Conducted emissions