black alloy one piece cantilever scope ring tactical system with anti-cant. Has see through design (with anti-cant removed). Suitable for any centrefire guns and .22 guns and airguns with a 20mm weaver / picatinny rail. fits 30mm scope tube and 1" scope tube with provided spacers. 40mm base to centre. 58mm between rings. 139mm overall length. + I have 222 Loctite listed and its recommended to use on the scope cap screws.