AT&T TL7800 Cordless Phone Battery Li-Pol, 3.7 Volt, 240 mAh - Ultra Hi-Capacity - Replacement for BT-191665 Rechargeable Battery Synergy Digital Replacement Battery for BT-191665 Li-Pol, 3.7 Volt, 240 mAh. Made with high quality Japanese cells. 100% compatible with your OEM battery - 3 year warranty. Synergy Digital is a Registered Trademark