Pryme SPM-3342 3-Wire Headset for Vertex Standard VX-120 127 170 177 6R 7R. 3-Wire SPM-3300 Series Heavy Duty 3-Wire Surveillance Kit: Features acoustic tube earphone with TWIST CONNECTOR, remote PTT switch and low-profile lapel microphone. Straight cable. The SPM-3300 Series is a heavy duty 3-wire surveillance kit. The kit features a clear acoustic tube earphone with TWIST CONNECTOR for easy removal, plus a small, covert microphone which can be clipped to the user's lapel or shirt sleeve, and a separate barrel style PTT which is held in the hand. Designed for high level of covert communications. Micro lapel mic can transmit under clothing. Barrel PTT form fits for easy transmission. TWIST CONNECT acoustic tube assembly for hygiene and multiple users. Reinforced earphone clip provides cable retention and eliminates strain on earphone.