Amazon.com: Synergy Digital SDCP-H326 - Ni-MH, 3.6 Volt, 850 mAh, Ultra Hi-Capacity Battery - Compatible with Panasonic HHR-P104, Type 29, Compatible with Sony MDR-RR800/900 Series Cordless Phone Batteries : Electronics
14500 3.6V 850mAh Lithium-Ion AA Size Rechargeable w/Wire Leads