Wilson Combat Bolt Upgrade Kit AR-15. These parts go beyond military specifications to improve your rifles performance. Specifications for Wilson Combat Bolt Upgrade Kit: Manufacturer: Wilson Combat Fabric/Material: Chrome Silicon Stainless Steel Package Contents: Wilson Combat Bolt Upgrade Kit MK3 Ejector Spring/USGI Ejector Spring Extra-Power Chrome Silicon Extractor Spring Stainless Steel Unitized Gas Ring with Four Turns What firearm models does the manufacturer say Wilson Combat Bolt Upgrade Kit is compatible with? The manufacturer suggests that Wilson Combat Bolt Upgrade Kit is compatible with AR-15 AR-10Wilson Combat TR-BUK-15: Bolt Upgrade Kit AR-15