The Luth-AR Modular Buttstock Assembly (MBA) for AR style carbines is designed to replace the standard buttstock on your AR. The MBA-4 with Cheek Rise is designed to work with a 6-position Mil-Spec or Commercial buffer tube. The MBA-4 with Cheek Rise is a direct replacement a standard adjustable carbine buttstock with an adjustable Cheek Rise in a low-cost, lightweight, strong and high-quality design. The MBA-4 requires a Carbine buffer tube, either Mil-Spec or Commercial. Please review the information provided in the Requirements tab. This stock works with both carbine Commercial and Mil-Spec tubes/assemblies. The MBA-4 also features an anti-rattle set screw. The modular design Mfg: Luth-Ar