The HM 100a open face helmet headset and PTT system is an accessory for use with Cobra pmr446 2 way radios . The HM 100a makes the use of a 2 way radio convenient and safe while riding a motorcycle snowmobile ATV or any other activity in which an open face helmet is worn. Use the HM100 in conjunction with your 2 way radio for bike to bike sled to sled and ATV to ATV communications while riding. The HM 100 features a open face helmet headset boom microphone with 2 ultra thin speakers and flexible boom microphone that attach quickly and easily inside the helmet. A weatherproof handlebar mount push to talk (PTT) switch puts control of the 2 way radio at your fingertips. Generous cable lengths and helpful accessories make installation easy and professional looking