DEFENDER MEDIUM-DUTY LAPEL MICROPHONE w/D-Shape Ear Hanger. The D ring fits over the ear to hold earpiece in securely in place. Patented swivel design can be used on either ear.
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.