Swing C Clamps use our patented left-hand-thread swivel-foot system. The ball end of the body screws into the foot for easy installation and removal. Once the ball threads pass beyond the foot threads, the foot can rotate and pivot freely (20° total angle). Foot threads are left-hand to positively prevent accidental back out during use. For other foot types, including Delrin® feet, see Feet for Swivel Screws in Related Products below.