Luth-AR A1 Delta Ring/Slip Ring Black 223 Caliber. First it can be used as a slip ring allowing the shooter to remove their hand guard to perform low volume cleaning or other tasks. Second it can be used as a trigger guard screw allowing the shooter to remove or replace the trigger guard on their lower receiver. The second purpose is to install the trigger guard screws that come with your A1 Delta Ring. Second it can be used as a delta ring allowing shooters to remove their hand guards. The only difference between a slip ring and a delta ring is that a slip ring can only be used on one trigger guard. With that being said it is assumed that a delta ring is only for the round delta ring. Specifications for Luth-AR A1 Delta Ring / Slip Ring: Manufacturer: Luth-AR Color: Black Fabric/Material: Aluminum Finish: Hard Coat Anodized Gun Make: AR Platform Caliber: .223 Remington Package Contents: Luth-AR A1 Delta Ring / Slip Ring Luth-AR BL-09A: A1 Delta Ring/Slip Ring Black 223 Caliber