Listen Technologies LT-700-216 Portable Display RF Transmitter (216MHz), Dark Grey, Superior Audio Quality, Mic and/or Line Level Inputs, Transmit Up to Three Channels Simultaneously Superior Audio Quality  80 dB signal-to-noise ratio, setting the industry's sound quality standard Look & Listen LCD shows channel, battery status, and programming information A choice between 57 channels, complete antenna and accessory options make Listen products ideal for a wide range of applications 100 % Digital  Listen receivers are digitally-tuned so transmission won't drift; assurance that when you select a channel, it stays on the channel Built in SmartCharge wont allow batteries to overcharge. Charging circuitry is conveniently built into Listens LT-700 Transmitter; never worry about unplugging a transformer at a certain time