ARKEN OPTICS Halo Series billet precision scope rings are CNC machined from 7075 aircraft-grade aluminum that have ZERO tolerances for errors in any conditions. With ARKEN&';s endless pursuit for precision, HALO rings are machined in pairs for ultimate accuracy and consistency. Torx style socket screws along with enhanced recoil lugs result in amazing stability and secure mounting. Arken Optics recommends max torque settings no greater than 18in/lb for ring screws and 30in/lbs for base screws. The optic manufacturer&';s specification shall always supersede Arken&';s Halo Rings specification, unless higher. Finish: Matte Black Material: 7075 T6 Aluminum Fit: MIL-STD picatinny rails.