Sennheiser BA 70.
The Sennheiser BA 70 is a rechargeable lithium-ion battery pack for the EW-D SK bodypack and EW-D SKM-S handheld transmitters. It can be used in place of the two AA size batteries to provide up to 12 hours of operation.
The L70 USB dual-charging station (available separately) is required for BA 70 batteries.
