2-Wire Surveillance Earpiece works with the Motorola DP3400/DP4000 range of 2 way radios,
these 2 wire kits have a PTT and Mic on the end of one wire and an acoustic clear tube on the other for clear, covert communications.
PTT: On mic, Vox: Yes
Programmable Button: Yes
Intrinsic Safety Standard: UL/TIA 4950