These ball socket head screws have a round or flat ball ends. The ball rotates in the screw socket as force is applied allowing contact to be maintained on moving or contoured surfaces as force is applied. The screw is made from SAE-4135 alloy steel with a black oxide finish. The ball is made from SAE-52100 alloy steel and hardened to Rc 56-60. These screws are used on CP100/101/102 series clamps, and BJ350/351 work supports.