3-1/2AA-K2 - Ni-CD, 3.6 Volt, 400 mAh, Ultra Hi-Capacity Battery - Replacement Battery for Cordless Phone Battery Replacement Battery- Ni-CD, 3.6 Volt, 400 mAh. 100% compatible with your OEM battery - 3 year warranty. Made with high quality Japanese cells. Synergy Digital is a Registered Trademark