Pro Mag floor plates add two additional rounds to Glock 9mm magazines and one additional round to the 40 S&W magazines. They provide an additional gripping surface for more positive control of the pistol. This 2-pack can convert two magazines with no permanent modification required. Type Floor Plate Model Floor Plate Finish Black Series Floor Plate Caliber 9mm Luger Capacity 2 Material Polymer Brand Fit Glock Model Fit Glock 9, 40