The Delta Series(R) AR 308 Mag well Block is designed for use with the Tipton(R) Best Gun Vise(TM). The vice block locks into the magazine well and provides a steady base for cleaning or light gunsmithing on your LR-308 Rifle.CAN BE MOUNTED DIRECTLY TO YOUR BENCH TOP WITH THE INCLUDED FASTENERS.LOCKS INTO PLACE USING MAGAZINE LOCK ON YOUR RECEIVER.BUILT-IN HAMMER STOP PREVENTS DAMAGE TO LOWER RECEIVER.SOLVENT-RESISTANT POLYMER PROVIDES DURABILITY AND IS NON-MARRING TO SURFACES.MAG WELL ARM IS REMOVABLE FOR CLAMPING IN A VISE.