Great for tire carriers, speaker brackets, bolt-on roll cage parts, or other accessories that must be removable. The KEY feature of these 6-bolt clamps is the Male Diamond Knurling. The "teeth" help lock the clamp in place and provide added gripping force/ anti-slip support. Designed and CNC machined in the USA from DOM tubing with beveled corners to provide a high-quality, fab-ready finish. NOW have zinc plated bolts!