The CAD Audio BPC1 Drop-In Battery Charger for WX155 Bodypack Transmitter is designed for easy charging of AA NiMH batteries without removing them from the WX155 transmitter. The BPC1 features overcharge protection and charge status lights. The units can be linked together utilizing the chassis keys on each side of the unit. The power can be daisy chained utilizing the DC In / DC Out plugs on the back of each unit. A maximum of 4 units can be tied together with one power supply. The charger draws power from a standard A/C power outlet, power adapter provided.