The rectangular permanent-magnetic chuck is the auxiliary fitting of various kinds of plain surface grinder, universal tool grinder and electro machining. Machine too etc. According to the structure, it can be classified as ordinary permanent-magnetic chuck, fine-pole permanent-magnetic chuck, single-inclination permanent-magnetic chuck and double-inclination permanent-magnetic chuck. The rectangular permanent-magnetic chuck are all used for holding ferromagnetic work piece for machining They are also used as tools of locksmith for skimming, marking and milling.