Necessary for installing a barrel onto an upper receiver and retaining drop-in style handguard. Comes fully assembled. Specifications for Tiger Rock AR-15 Delta Ring Kit w/ Delta Ring, Snap Ring, Weld Spring & Barrel Nut: Manufacturer: Tiger Rock Condition: New Color: Black Fabric/Material: Heat Treated Steel, 6061 Aluminum Quantity: 1 Finish: Anodized Included Accessories: Standard Handguard Type: Drop-In Gun Make: AR Platform Gun Rail: Standard Gun Type: Rifle Gun Model: AR-15 Features of Tiger Rock AR-15 Delta Ring Kit: Barrel Nut: Heat treated Steel construction; Phosphate finish Snap Ring: 6061 Aluminum construction Phosphate finish Weld Spring: 6061 Aluminum construction Phosphate finish Delta Ring 6061 Aluminum construction Black Anodized finish Package Contents: Tiger Rock AR-15 Delta Ring Kit with Delta Ring, Snap Ring, Weld Spring, Barrel Nut