Visionking Rifle Scope Rings 25.4mm 30mm Tube Mount Ring for .223 .308 .50 Cal 11mm Low High Shockresistance Body Material: High quality 6061 Weight(g): 180g(before packing) Ring Diameter: 25.4mm/30mm This rifle scope mount fits for rifle scope with 25.4mm or 30mm tube.Fits for 11mm rails.With high quality 6061 aluminum and six bolts it can load heavy duty up to .50 cal.