OEM Motorola PMNN4424 IMPRES 2300 mAh Li-Ion, submersible and Intrinsically Safe (IS) battery.  

Compatibile with APX 4000/3000/1000.

IMPRES batteries when used with an IMPRES charger provide automatic, adaptive reconditioning, end-of-life display, and other advanced features. Data is stored in the battery and communicated to the charger via a unique IMPRES communication protocol which is designed to maximize talk-time and optimize battery cycle life — all automatically.