Zebra Wired Headset (HDST-25MM-PTVP-01) - Mono - Sub-mini phone (2.5mm) - Wired - Earbud, Over-the-ear - Monaural - Outer-ear - Black MC40 REV B 2.5MM Headset for PTT + VoIP. Headset includes rotating ear piece for right/ left ear configuration & built in cord wrap. QTY-1. NOTE: headset is only compatible w/ Android JellyBean OS (4.1.1) with Rev B. This headset will not work on older versions of MC40.