These Chucks are known as Master and Top Jaws Chucks.In these chucks the Jaws are manufactured in Two Parts. One set of Base Hard Jaws(Master Jaws) fitted in the body and second part Top Hard Reversible,which is possible to mount on Base Hard jaws in Forward & Reverse positions with the help of Allen bolts.The Soft Jaws are also mountable on the same base hard jaws which is modified as per requirement. One Set of the Soft jaws is supplied along with each chucks. The Chucks are available from 160mm to 610mm sizes.