hi, i'm planning on buying this sight online(High Quality Optical Products, Rifle Scopes, Binoculars, Spotting Scopes and Accessories), but i'm not sure if it will fit on my rail. all i can find about the sight mount is that is a "5/8 weaver style attachment." i don't understand what that means so does anyone know if this will fit on my standard 20mm picatinny weaver rail? and if not what type of rail will a need?