Anyone with average- to small hands now can easily perform magazine changes without shifting their firing grip on the weapon. The GMR-004 is easy to install"" and made of the same tough polymer as the Glock factory part. The extended catch is just perfect"" not too short"" not too long"" i.e. the magazine will not accidentally release if pistol is laid on a hard surface. Perfect with use of back strap mounted lasers. Ambidextrous. For Gen 4 pistols only.