Centennial Defense Systems Guide Rod Recoil 15lb Spring for Gen 4 Glock 20. Our springs are designed for CDS guide rods but may work with other brands. Specifications for Centennial Defense Systems Guide Rod Recoil Spring for Gen 4 Glock 20: Manufacturer: Centennial Defense Systems Color: Stainless Steel Fabric/Material: Stainless Steel Gun Make: Glock Gun Model: Glock 20 Package Contents: Centennial Defense Systems Guide Rod Recoil Spring for Gen 4 Glock 20 What firearm models does the manufacturer say Centennial Defense Systems Guide Rod Recoil Spring for Gen 4 Glock 20 is compatible with? The manufacturer suggests that Centennial Defense Systems Guide Rod Recoil Spring for Gen 4 Glock 20 is compatible with Glock 20Centennial Defense Systems 14547: Guide Rod Recoil 15lb Spring for Gen 4 Glock 20