Pearce grip's magazine extension adds capacity to mid and full size glock high capacity magazines.It replaces the original floor plate and internal locking plate and adds two rounds to a 9mm; two rounds to a 40sw and 357sig, and one round to a 45gap magazine.Caliber: 9mm LugerCapacity: 2rdFinish: BlackModel: Magazine ExtensionMaterial: PolymerType: Magazine ExtensionModel Fit: Mid & Full SizeBrand Fit: GlockCapacity: 2