Replacement Motorola RDU4100 FBI Earpiece with Push to Talk (PTT) Microphone - Acoustic Earphone For Motorola RDU4100 Radio - Headset for Security and Surveillance Replacement Motorola RDU4100 Acoustic Earpiece with Push to Talk (PTT) Microphone Transparent coiled acoustic tube provides clear audio quality in any type of environment Lightweight flexible and skin friendly materials adds comfort for extended wear time The earpiece wraps behind your ear plus the rotating lapel clip works together to give a more secure fit. Low profile design for a stealth look and feel with convenient PTT push to talk button prevents unwanted or accidental radio transmission . UpStart Battery Brand. On Sale for a Limited Time!