The 4Ah lithium ion battery is designed to deliver extended run times to our compact handheld tools where weight and easy handling are prime considerations. Weighing just 720g this powerful 10 cell battery charges in just 50 minutes due to our smart charging technology Fitted with an intelligent battery management system that protects them from over voltage, over current and over temperature degradation All Evolution EXT battery packs are compatible with Erbauer 18V EXT Cordless Tools.