BATT-50 - Li-Ion, 2.4 Volt, 600 mAh, Ultra Hi-Capacity Battery - Replacement Battery for Sony BP-T50 Cordless Phone Battery Replacement Battery for Sony BP-T50 -NI-CD, 2.4 Volt, 600 mAh. 100% compatible with your OEM battery - 3 year warranty. Made with high quality Japanese cells. Synergy Digital is a Registered Trademark