GP GP30AAK3BMJ Cordless Phone Battery Ni-MH, 3.6 Volt, 700 mAh - Ultra Hi-Capacity - Replacement for Sony BP-T27Rechargeable Battery Replacement Battery for Sony BP-T27- Ni-MH, 3.6 Volt, 700 mAh. 100% compatible with your OEM battery - 3 year warranty. Made with high quality Japanese cells. Synergy Digital is a Registered Trademark