Motorola RLN4941A Remote Speaker Microphones with 3.5mm Audio Jack (Black/Clear) Earpiece plugs into all Remote Speaker Microphones 3.5mm unthreaded audio jack on the head of the microphone. The clear tube provides a more discreet option for those that need to receive messages privately An earphone jack located on the microphone allows the user to receive audio when using this earpiece Compatible, APX 4000, APX 6000, APX 6000XE, APX 7000, APX 7000XE, ASTRO Saber, BPR40, CP125, CP150, CP185, CP200, CP200-XLS, CT150, CT250, CT450, CT450-LS, EX560-XLS, HT1250-LS, HT1550-XLS, LTS 2000, MT 2000, MTS 2000, MTX8250-LS, and more.