Six cap screws and double clamp bolts with 1⁄2" nuts, solidly lock scope, rings and base into one unit. Prevents large objective 30mm scopes from slipping under recoil on .50 BMG rifles. Povides clearance for 56mm objective scopes. Square cross bolts provide secure, ring-to-base contact with excellent return to zero. Wire EDM cut from bar stock and stress relieved. Fits Picatinny rails only. Mfg: Smith Enterprise SPECS: 4140 steel, parkerized, matte finish. Rc 35. Fits 30mm dia. scope tubes. .685" (17.4mm) high from top of base to inside bottom of ring.