This is a 5/8 inch or 16mm pin for squatrack or powerrack. It is made to be used on a 3x3 or 75x75 rack. But i guess it fits on smaller rack sizes with the same pin hole. It is not intended to bear any significant weight. Its for stabilizing j-hooks for example. I have made it with holes for small magnets to make it stick to the rack and doesnt creep out. I made mine with PLA