Other great features of the AH8 Headset Transmitter include an internal 8-hour rechargeable lithium ion battery, easily accessible Gain and Mute controls, and IR sync to wirelessly match the receiver and transmitter frequency. Designed with Yoga, Pilates, Zumba and cycling instructors in mind, the system's headset features water-resistant components, including a marine-grade stainless steel gooseneck, sealed circuit board and AE50X micro-miniature microphone capsule. The capsule's cardioid pickup pattern prevents feedback and other unwanted noise from affecting a performance. Offering frequency-agile operation, the system's rack mountable CR88 Wireless Receiver provides 16 selectable channels for reliable performance no matter where you are. The receiver's True Diversity design minimizes dropouts, while tone key technology prevents unwanted noise when your transmitter is off or out of range. For classes with more than one instructor or facilities with multiple studios, up to eight systems per frequency band can be used simultaneously.