Usually there are 12 categories which are bolt , stud, screw, nut , self tapping screw, wood screw, gasket, retainer ring, pin, composite member, bolting, and soldering lamp.

它通常包括以下十二类零件：螺栓、螺柱、螺钉、螺母、自攻螺钉、木螺钉、垫圈、挡圈、销、组合件和连接副、焊钉等。