These chucks are self-centering lathe chucks with special jaws. These chucks are manufactured in two parts. One set hard jaws fitted in the body and second part top reversible which is possible to reverse back and use in opposite direction. These chucks do not require an extra set of jaws. They are available in 3, 4 Jaws and of sizes range from 160 mm (6 inches) and 210 (8 inches).