Pearce grip's plus extension replaces the magazine base plate and internal floor plate.It will add three rounds to the glock 26, two rounds to the glock 27 and 33, and one round to the glock 39.It will also add 1" additional length for better control and comfort.Caliber: 9mm Luger/40 Smith & Wesson (S&W)/357 Sig/45 GAPCapacity: 3rd (9mm), 2rd (40 S&W), 1rd (45ACP)Finish: BlackModel: Plus ExtensionMaterial: PolymerType: Magazine ExtensionModel Fit: G26,27,33,39Brand Fit: GlockCapacity: 3 (9mm), 2 (40 S&W), 1 (45ACP)