Sony BPT38 Cordless Phone Battery Ni-CD, 3.6 Volt, 900 mAh - Ultra Hi-Capacity - Replacement for Sony BP-T38 Rechargeable Battery Synergy Digital Replacement Battery for Sony BP-T38 Ni-CD, 3.6 Volt, 900 mAh. Made with high quality Japanese cells. 100% compatible with your OEM battery - 3 year warranty. Synergy Digital is a Registered Trademark