The Lipo Charging and Storage Safe Bag is made from Kevlar with an aluminum coating, the same material as fire fighter’s clothes! This combination of Kevlar and Aluminum provides superior fireproof protection. EM Charge bags are offered in two sizes, Large and Small. The large bag will fit 2 medium to large Lipo batteries. The small bag offers the same great protection, in a size that will fit 2 small to medium Lipo batteries.