The Salmon River Solutions family of ARCA rails are not only the lightest ARCA rails on the market but also the only ARCA rails available that match well to a rounded style hunting stock. Made from 7075 aluminum, SRS came up with an extremely light rail while utilizing a full-length slot for flexible mounting options. Bolt spacing is 1" to 3.25". Each rail comes with 10-32 screws and M-Lok mounting hardware, to provide compatibilty with a wide range of forends.