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 fine-pole chuck is more suitable for processing of thin & small work piece. Because it is without requiring power source, without heating and with high precision, it is widely applied in machinery processing industry.