The AC-CSF28 clamp was designed with a 1/4"-28 fine thread bolt allowing a more precise adjustment . It has 30 degrees of side to side movement and measures 1 1/2" between the centers of both ball mounting holes. It comes with a redesigned black knob and works with any 1" ball. Made out of 6061 T6 aircraft-grade aluminum with Type III anodizing . Will work in the harshest of environments, time proven and built to last.omes with a redesigned black knob. Made out of 6061 T6 aircraft-grade aluminum with Type III anodizing . Will work in the harshest of environments, time proven and built to last.