This is one of the most useful maintenance accessories available for an AR-10. Simply bolt or clamp securely to a bench or other work surface, place an AR 308 rifle onto the block inside the magazine well, and the rifle is held in place for cleaning, maintenance, or storage. 1-piece glass filled polymer design Fits rifles that use SR-25 pattern magazines Weight: .7oz 6-1/8" tall x 2" long(at the base) x 4-1/4" wide (at the base) 1/4" mounting holes Mfg: Ergo Grips