These Vortex Precision Matched 30 mm (.87 Inch / 22.1 mm) Rings feature a tight tolerance of .0005” and are milled out of 7075 T6 aluminum. The precision matched rings are made to last with a Type 3 hard coat and offer an anti-snag design. At only 2.1 ounces, they are light enough to not add any noticeable weight to your rifle set up.