Radio Shack 23-970 Cordless Phone Battery Ni-MH, 2.4 Volt, 1500 mAh - Ultra Hi-Capacity - Replacement for Panasonic HHR-P509 Rechargeable Battery Replacement Battery for Panasonic HHR-P509 - Ni-MH, 2.4 Volt, 1500 mAh. 100% compatible with your OEM battery - 3 year warranty. Made with high quality Japanese cells. Synergy Digital is a Registered Trademark