The AH1 Headset Transmitter is designed to go around the back of your head rather than over the top. This allows the transmitter to be attached directly to the headband, out of the way and completely unobtrusive, while being comfortable and secure during performances. The AH1 offers 14 hours of operation on a single AAA battery. For the AirLine 77 Fitness Headset system, the AH1 Headset Transmitter features Samson's Qe condenser microphone element. The Qe is designed with a unidirectional microphone and cardioid pickup pattern that rejects feedback. It's ideal for group fitness instructors who need a durable headset microphone that will remain in place despite repetitious movement.