Li-Polymer Battery for Sennheiser MM 400-X MM 450 MM 450-X 3.7V 270mAh
Fit to the device models:Sennheiser 450 TRAVEL, 550 Travel, MM 400, MM 400-X, MM 450, MM 450-X, MM 500-X, MM 550, MM-550-X, PCX 360 BT, PX 210 BT, PX 310 BT, PX 360, PX 360 BT, PXC 310, PXC 310 BT, PXC 360 BT.