Luth-AR 16 in Light Weight Complete Upper Barrel Receiver Assembly - 5.56 1x7 twist M-LOK Free Float Handguard Black 16. 56mm Lightweight barrel made from 4140 Chrome Molly with a 1-9 in twist mated to our A3 Flattop receiver which includes our bolt carrier charging handle forward assist and ejection port cover. The upper is then topped off with our lo-profile gas system and our ergonomic 15 in Palm Handguard with KeyMod or M-LOK slots and a Picatinny top-rail. Specifications for Luth-AR 16 in Light Weight Complete Upper Barrel Receiver Assembly: Manufacturer: Luth-AR Caliber: 5.56mm Overall Length: 26 in Barrel Length: 16 in Barrel Profile: Light Weight Threads per Inch: 1/2x28 Handguard Type: Free-Float Muzzle Device: A2 Flash Hider Finish: Anodized Color: Black Gun Model: AR-15 Fabric/Material: Aluminum Gas Block Journal Size-Diameter: .750 in Handguard Length: 15 in Gun Rail: M-LOK Magazine Included: No Mount Type: M-LOK Package Contents: Luth-AR 16 in Light Weight Complete Upper Barrel Receiver Assembly What firearm models does the manufacturer say Luth-AR 16 in Light Weight Complete Upper Barrel Receiver Assembly is compatible with? The manufacturer says that Luth-AR 16 in Light Weight Complete Upper Barrel Receiver Assembly is compatible with AR-15Luth-AR BA-L16-7M: 16 in Light Weight Complete Upper Barrel Receiver Assembly - 5.56 1x7 twist M-LOK Free Float Handguard Black 16