The Sig Sauer ALPHA1 Aluminum Hunting Rings are proprietary 6061-T6 aluminum alloy rings that are machined with an exactness that is both strong yet ductile that allows them to form around a riflescope, yet will not damage scope under proper installation. These aluminum rings are epoxy powder coated to prevent oxidation and resist gun oils, cleaning solutions, and outdoor exposure. There are 15 models available that include 30mm, 34mm, 35mm and 1 inch diameters.