Made from Hardened A2 tool steel, these clamps swing out of the way when clamp screw is loosened. When the clamp screw is tightened the clamp swings back into position. These are great for second operation fixtures and take up very little space on the fixture. The differential screw is included. Simply add a 1/4 x 28 hole and a 3/8 by 3/8 deep slot to your fixture.