The Sony DWT-B01 Digital Wireless Bodypack Transmitter is intended for use with Sony lavalier microphones such as the ECM-77BC/9X or ECM-FT5BC and features digital audio processing for lower noise and a longer, efficient range. Up to three selectable output power settings are provided for maximum results and improved battery efficiency. Two AA alkaline batteries power the DWT-B01 for up to 5 hours at the 10mW power setting. Additional features include an input attenuator, RF frequency selection, RF power output, Audio LCF frequency, and a power sleep mode (in the transmitter) that can be remotely controlled from the DWR-S01D digital wireless receiver (available separately).