18v, lithium-ion battery, bosch exclusive cool-pack 2.0 technology provides up to 135% more battery life than batteries without, 1.8 lb provides performance comparable to batteries that are up to 35% larger, features backward & forward compatibility with all bosch 18v tools & chargers, charges to 80% in only 41 minutes & 100% in only 55 minutes using the optional bosch bc1880 18v fast charger, works in cold weather conditions down to -4 degrees.