If you need a baby pin mounted to something super thick, this is your clamp. The jaws open to 6 inches wide, and are coated with a rubber pad to provide extra grip. The shape of the jaws allow you to clamp to irregular surfaces like cinder blocks or a thick beam. You should only use this clamp for thick surfaces. It is not designed to be used with speedrail or other smaller-diameter tubes, as the mount will be too far from the jaws.