The 18V 4.0Ah Lithium Ion Battery BSL1840M (378681M) is a powerful, long-lasting battery for all of the Metabo HPT 18V slide-type power tools. It delivers increased productivity and run-time thanks to the large 4.0 Amp Hour (Ah) capacity. The Amp hour capacity refers to how long the battery can last before recharging. This impressive 18V 4.0Ah Lithium Ion battery can be used to power all Metabo HPT 18V slide type cordless tools and products. For protection from the elements, this battery features a resin coating. Its complex circuitry also prevents damage from overload, overcharge, and over-discharge of the battery. The Metabo HPT battery is warranted to the original purchaser to be free from defects in materials and workmanship for a period of 2-years from the original purchase date. Every Metabo HPT accessory is designed to the highest standards and is rigorously tested for both performance and durability.