JL Billet Replacement Barrel Nut Key Seat AR/15 Black. Specifications for JL Billet AR-15 Replacement Barrel Nut Key Seat: Manufacturer: JL Billet Color: Black Gun Model: AR-15 Condition: New Fabric/Material: Stainless Steel Weight: 0.1 lb Mount Type: M-LOK Country of Origin: USA Package Contents: JL Billet AR-15 Replacement Barrel Nut Key Seat What firearm models does the manufacturer say JL Billet AR-15 Replacement Barrel Nut Key Seat is compatible with? The manufacturer suggests that JL Billet AR-15 Replacement Barrel Nut Key Seat is compatible with AR-15JL Billet JLB-556-KEY: Replacement Barrel Nut Key Seat AR/15 Black