Centennial Defense Systems MOD1 Stainless Steel Guide Rod Assembly for Smith & Wesson SD9 & SD40 4in Barrel 11lb Stainless Steel No Coating. This eliminates guide rod flex and ensures it will not chip crack or break like plastic guide rods providing a lifetime of reliable service. Flat wound recoil springs are manufactured of certified aerospace spec materials heat treated shot peened and stress relieved to maximize durability. The screw tip is easily removed to allow the user to change spring weights and fine tune the recoil spring to the ammunition of choice. Specifications for Centennial Defense Systems MOD1 Stainless Steel Guide Rod Assembly for Smith & Wesson SD9 & SD40 4in Barrel: Manufacturer: Centennial Defense Systems Fabric/Material: Stainless Steel Gun Make: Smith & Wesson Gun Model: Smith & Wesson SD40 VE 4in Smith & Wesson SD9 VE 4in Package Contents: Centennial Defense Systems MOD1 Stainless Steel Guide Rod Assembly for Smith & Wesson SD9 & SD40 4in Barrel What firearm models does the manufacturer say Centennial Defense Systems MOD1 Stainless Steel Guide Rod Assembly for Smith & Wesson SD9 & SD40 4in Barrel is compatible with? The manufacturer says that Centennial Defense Systems MOD1 Stainless Steel Guide Rod Assembly for Smith & Wesson SD9 & SD40 4in Barrel is compatible with Smith & Wesson SD9 VE 4in Smith & Wesson SD40 VE 4inCentennial Defense Systems 11801: MOD1 Stainless Steel Guide Rod Assembly for Smith & Wesson SD9 & SD40 4in Barrel 11lb Stainless Steel No Coating