Bosch BAT420 12-Volt Max 4.0Ah High Capacity Battery 2x the Run Time: Twice the run time compared to existing 2.0Ah and nearly 3-times more run time over 1.3Ah battery by using high quality Li-Ion cells Most Compact: Smallest and lightest battery pack with 4.0Ah in the market Performs in cold temperatures down to -4 degrees F Compatible with all Bosch 12-Volt Max Tools and chargers