DEFENDER series QD® QUICK-DISCONNECT Lapel Microphone w/C-Shape Ear Hanger. The unique C style earpiece is similar to the popular D style but ADJUSTABLE so can fit any ear size.
Fits many HYT models including: TC-1600, TC-500, TC-600, TC-610, TC-620, TC-700, TC-700EX
Very similar to the Motorola 2-pin except this one has a screw to lock it in place.