Panasonic KX-TG4321 Cordless Phone Battery Ni-MH, 1.2 Volt, 1000 mAh - Ultra Hi-Capacity - Replacement of Pack of 4 AAA Batteries Replacement Batteries for Rechargeable AAA - Ni-MH, 1.2 Volt, 1000 mAh. 100% compatible with your OEM battery - 3 year warranty. Made with high quality Japanese cells. Synergy Digital is a Registered Trademark