Pack of 20 Universal Heavy Duty Exhaust U Bolt Clamps complete with nuts. Made from mild steel and zinc plated for anti-corrosive properties. These clamps have a variety of uses including exhausts, TV aerials, framing fasteners, and anchors. Available in sizes ranging from 28mm to 130mm. The measurement refers to the inside diameter. For example, a 52mm clamp has 52mm between the inside of the legs. Manufacturer: Homesmart.