RIDGID introduces the 18V Lithium-Ion (2) 4.0 Ah Battery Starter Kit with Charger and Bag. These batteries get up to 4X the runtime of standard lithium-ion batteries and are built for high performance and are protected from overheating, overloading and overcharging through their Triple Protection Electronics design. Their chemistry allows for maximum performance in temperatures as low as -4 degrees and up to 120 degrees F, so you can confidently use them year-round. The charger is compatible with all RIDGID 18V Batteries.