This Brand Battery VARTA is the only recommended one with the battery level indicator to let you is it is going low. If you do not use this battery the tracker will just run out of power with no warning. Moni Moto Tracker Batteries Requires 2 Technical specifications: VARTA type: 6205 Int. Frame size: CR123A Capacity: 1550 mAH Voltage: 3.0V   Electrochemical system: lithium Diameter: 17.0 mm Height :: 34.5 mm Weight: 17.0 g