American Defense Offset RMR mount. Available in 33 and 45 degree offsets, with Right or Left hand mounting. Left Hand mount will place the optic on the Left Side of the rifle. Right Hand mount will place the optic on the Right Side of the rifle. The mount requires ½ of clearance under the scope tube or eye piece to fit under the scope.The base is 1.35†long. The 33* model was designed as a low profile offset RMR Mount. The 45* is for use with the ACOG and scopes with large adjustment caps. Weight- 3oz