Bosch SKC180-03 18-Volt Lithium-Ion Starter Kit with 2 Batteries, Charger and Case Flexible power system-choose minimum weight or maximum runtime for all Bosch 18V lithium-ion tools Electronic cell protection - monitors battery to prevent cell damage caused by overheating Heat conductive housing - pack design allows for faster heat dissipation No memory effect-charge batteries at any time without risk Less power fade during use-tools work at top performance throughout discharge cycle