1. . 2. It enables you to talk and listen without having to move the radio. Just clip the mic where convenient and use it to listen and transmit. 3. Works with mobile radios with 8-pin RJ connector. Compatible Models: For TM-231, TM-241, TM-731A, TM-631A, TM-201A, TM-401A, TM-201B,TM-401B, TM-211A, TM-411A, TM-221A, TM-321A, TM-421A, TM-521A, TM-231A,TM-331A, TM-431A, TM-531A, TM-241A, TM-441A, TM-541A, TM-701A, TM-721A, TM-621A,TM-2530A, TM-2550A, TM-2570A, -4100A, -4000A 8pin Material:ABS colour:black Package Contents: 1 * Speaker Mic for Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.