NOCO MC303 NCP2 Battery Terminal Protectors are designed to provide a barrier against acid vapors that leak through improperly sealed batteries and cause battery corrosion. Each battery terminal protector is made from 100% organic non-woven felt and impregnated with NCP2 Battery Corrosion Prevention Compound. It lasts indefinitely without drying out or evaporating and is guaranteed for the life of the battery. Suitable for top and side mount batteries.