Luth-AR MBA-4 Buttstock is a lightweight, skeletonized carbine buttstock for AR-style rifles, compatible with both Mil-Spec and Commercial 6-position carbine buffer tubes (uses 4 of 6 positions). Constructed from super-strong glass-reinforced nylon in black. Fits .223 and .308 AR carbine rifles; not for large bore calibers. Length 10.375, weight 9.60 oz. Features bottom Picatinny rail and anti-rattle set screw. Includes 3/32 Allen wrench for set screw adjustment. Compatible with optional cheek piece and 3-axis butt plate assemblies (sold separately). Not compatible with A2 standard tubes. Sling swivels and buffer components sold separately. Safety note Follow all manufacturer installation instructions. Verify proper function and secure mounting before use. Comply with local firearm laws and regulations.