High Quality, high capacity rechargeable battery. No memory effect. Can be charged or discharged as needed without loss of capacity. Overcharge protection, with built-in battery life microchip. Volts: 2.4V Battery Type: Ni-MH Capacity: 60mAh Dimension: 15.00 x 20.00 x 35.00mm Compatible Part nos: SENNHEISER - BA150, BA151, BA152, WEST-BA151, WILLIAMS SOUND - BATAP97A Compatible Models: Sennheiser A200, RI250, RI250-J, RI250S