The Centennial Defense Systems Stainless Steel Guide Rod Assembly is a dual spring, complete drop in unit made from solid stainless steel. This eliminates guide rod flex and ensures it will not chip, crack or break like plastic guide rods providing a lifetime of reliable service. Recoil springs are manufactured of certified materials, heat treated, shot peened and stress relieved to maximize durability. Specifications for Centennial Defense Systems Stainless Steel Guide Rod Assembly for Gen 4 Glock 20: Manufacturer: Centennial Defense Systems Fabric/Material: Stainless Steel Gun Make: Glock Gun Model: Glock 20 Model Generation: 4 Package Contents: Centennial Defense Systems Stainless Steel Guide Rod Assembly for Gen 4 Glock 20 Which weapon models is Centennial Defense Systems Stainless Steel Guide Rod Assembly for Gen 4 Glock 20 compatible with? Centennial Defense Systems Stainless Steel Guide Rod Assembly for Gen 4 Glock 20 is compatible with Glock 20