Centennial Defense Systems Extended Mag Release w/2.5lb Spring for Gen 4-5 9mm .40S&W .357SIG Glock Serrated Black. It is designed to fit in most holsters and will fit Gen 4-5 Glock models in 9mm .40 S&W .357 Sig. Included with the magazine release is our stainless steel mag catch spring available in the stock 5lb or reduced 2.5lb weight. The reduced 2.5lb spring cuts the weight in half for quicker mag drops and less resistance during magazine swaps. Note: Will NOT fit G42 G43 or Gen 1-3 pistols. Specifications for Centennial Defense Systems Extended Mag Release w/2.5lb Spring for Gen 4-5: Manufacturer: Centennial Defense Systems Gun Make: Glock Gun Model: Glock 25 Glock 35 Glock 34 Glock 24 Glock 22 Glock 17 Glock 33 Glock 27 Glock 26 Glock 32 Glock 31 Glock 23 Glock 19 Fabric/Material: 6061 Aluminum Condition: New Package Contents: Centennial Defense Systems Extended Mag Release w/2.5lb Spring for Gen 4-5 What firearm models does the manufacturer say Centennial Defense Systems Extended Mag Release w/2.5lb Spring for Gen 4-5 is compatible with? The manufacturer suggests that Centennial Defense Systems Extended Mag Release w/2.5lb Spring for Gen 4-5 is compatible with Glock 19 Glock 23 Glock 31 Glock 32 Glock 26 Glock 27 Glock 33 Glock 17 Glock 22 Glock 24 Glock 34 Glock 35 Glock 25Centennial Defense Systems 20709: Extended Mag Release w/2.5lb Spring for Gen 4-5 9mm .40S&W .357SIG Glock Serrated Black