Troy M-LOK rails are machined from hardened aircraft aluminum with stainless steel components and finished in MIL-SPEC hardcoat anodizing, the M-LOK rails are light and sleek. Easy to install and mount accessories. Proprietary Barrel Nut Included. Please note that the M-LOK rail is not compatible with the RRA LR8 or DPMA Gen 2 308 or .308 Ruger Precision Rifle. Mfg: Troy Industries, Inc.