Glock 20/21 Gen5 Recoil Spring Assembly Features The Glock 20/21 Gen5 Recoil Spring Assembly is built as a dual spring unit designed specifically for the .45 ACP and 10mm Gen5 platforms where it manages slide velocity and felt recoil during cycling. It is manufactured from polymer to the same factory specification as the part that ships as standard equipment on these pistols so fit and function match the original exactly. The 0-4-1 marking identifies it as the correct assembly for the Gen5 Glock 20 and Glock 21 helping owners and armorers select the right replacement part with confidence. Factory replacement parts like this one restore a pistol s original cycling characteristics without introducing an unknown aftermarket variable. Owners looking for a different feel can consider an upgraded stainless steel or tungsten guide rod which Glock also offers in a variety of spring weights for more durability and recoil reduction. Keeping a factory spare recoil spring assembly on hand is a simple low-cost way to maintain reliable function in a duty or carry pistol. Replacing a worn recoil spring at recommended service intervals helps prevent premature wear on other components and keeps the slide cycling consistently. This assembly is a straightforward drop-in part suited to routine maintenance by the owner or a qualified armorer working on Gen5 Glock 20 and 21 pistols. Glock 20/21 Gen5 Recoil Spring Assembly Specifications Manufacturer: Glock Model: 20/21 Gen5 Recoil Spring Assembly Type: Spring Compatible Hosts: Glock 20 Gen5 Glock 21 Gen5 Material: Polymer Available At: GrabAGun