Silent Capture Bolt Extension Gen 3 Folder - The Sylvan Arms Silent Capture Bolt Extension is hollowed out allowing you to run silent capture buffer spring systems with our Gen 3. Folding Stock Adapter . Designed for a 5/8 (.625) in. ID Bolt Carrier. Make sure that this will fit your configuration before purchasing! Will not fit Gen 4 Folder Compatible with the following Silent Capture Buffer Spring Systems JP Enterprise Silent Captured Springs Armaspec SMB Sound Mitigation Buffer Currently will NOT work with the Armaspec Stealth Recoil Spring Product Details O-ring Diameter: .645 in. Designed for a 5/8 (.625) in. ID Bolt Carrier Inside Diameter: .469 in. Length: 3.423 in. Weight: .6 oz. Material: 6061-T6 Aluminum Finish: Black Anodized If have any questions, feel free to contact us before ordering!