BBM supplies the Lithium Keeper LTC-3PN-S2 Battery - this battery is a 3.5V/350mAh Lithium 2 pin battery.
LTC-3PN-S2 Battery Specifications:
Device Manufacturer: Speciality Lithium
Voltage: 3.5 V
Capacity: 350 mAh
Chemistry: Lithium Thionyl Chloride
Terminal Type: PC Pins
BIN-703