Available in both four-screw and six-screw versions. Crafted of machined 7075-T6 hard anodized aluminum, with titanium crossbolts and jaws, these Nightforce rings give you the performance of steel at half the weight. This unique construction provides strength well beyond that normally found in lightweight rings.The four-screw ring will provide a lifetime of service for most applications. If you think you need 50 more clamping force, the six-screw Ultralite rings will hold your riflescope under any conceivable situation. NIghtforce Ultralite rings are offered in six heights for 30mm tubes and four heights to fit 34mm tubes.