700mAh Ni-MH Replacement Battery for Sony MDR-RF4000, MDR-RF840 and RF850, MDR-RF810 (plus other models detailed in Description) Wireless Headphones Capacity: 700mAh / 1.68Wh Type: Ni-MH Volts: 2.4V Size : 46.00 x 23.00 x 11.00mm Certificated with ISO9001, RoHS & CE;