CNC Stainless Steel/Aluminum Spring Guide Thru-Hole is specifically designed for Bolt Recoil Shock System (BRSS) to keep the spring in line and allow the spring to rotate on shaft during high compression. This Spring Guide Thru-Hole is machined with a 6.8mm through hole on stainless steel hub to allow the pushrod to go through thrust bearing and spring guide without any restriction. The Spring Guide Thru-Hole is also equipped thrust ball bearing to reduce spring stress and breakage during high speed spring compression. Made of Stainless Steel and Aluminum. Includes 1 x CNC Stainless Steel/Aluminum Spring Guide Thru-Hole Specification Hub Thru-Hole Diameter: 6.8mm Hub Outer Diameter: 16mm Shaft Outer Diameter: 10.8mm Shaft Inner Diameter: 7mm Shaft Length: 44.5mm Overall Length: 51.5mm Material: Stainless Steel and Aluminum Features Specifically designed for Bolt Recoil Shock System (BRSS) Stainless Steel and Aluminum construction Machined 6.8mm through hole on stainless steel hub Allowed the pushrod to go through thrust bearing and spring guide without any restriction Equipped thrust ball bearing to reduce spring stress and breakage Aligned spring in line and rotate on shaft during high compression Strong stainless steel hub chamfer shoulder designs