Panasonic KX-T4550 Cordless Phone Battery Ni-MH, 3.6 Volt, 750 mAh - Ultra Hi-Capacity - Replacement for Panasonic HHR-P301 Rechargeable Battery Replacement Battery for Panasonic HHR-P301 - Ni-MH, 3.6 Volt, 750 mAh. 100% compatible with your OEM battery - 3 year warranty. Made with high quality Japanese cells. Synergy Digital is a Registered Trademark