These units replace the magazine base plate and internal floor plate. They will add two rounds to the Glock 26, one round to the Glock 27 and 33 and no rounds to the Glock 39. These units will add 5/8" additional length for better control and comfort.FeaturesBlends with the contours and fourth generation texture of the handgun giving a factory appearanceMade from High Impact Polymer and withstand drop tests at temperatures from -20 F to 350 FForms the next logical finger positioning feature to provide control and comfort without sacrificing conceal ability DISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.