High-performance rechargeable lithium battery 5000mAh for DigiTrak® and Subsite® transmitters. Recommended Digitrak® FTA2 Rechargeable Lithium Battery Adapter is required for use with a standard size DigiTrak transmitter. The cell is 21700 with an impressive 5000mAh capacity and rechargeable back up to 100% within 2 hours. The battery can be recharged over 500 times. The design of the battery cell features multiple safety features and built-in protection that is suitable for HDD applications: PTC overcurrent protection, microporous insulation protection, pressure relief valve, and high-performance IC protective plate.