Ghost gen 4 ext.Mag release fits most glocks gen4 FEATURES-For Glock Gen 4 .45 ACP & 10mm-No pistol modification-Operate magazine release without changing finger grip-Maximum surface area-Drop-in-Fits Gen 4 models 20, 21, 29, 30, 40, 41 Other Features: Easy to install drop in/ no mods to frame max surface area for fast mag changes fits glock gen 4 models 17, 19, 22, 23, 26, 27, 31, 32, 33, 34, 35, 37, 38, 39.