A poppet consists of two principal pieces, one of which is a stud fastened to the table of the machine, or to a chuck of a lathe, and the other piece is a screw-bolt that fits one or two holes in the poppet, the head of the bolt being generally square or six sided. A general shape for poppets, whether small or large, is denoted by Fig. 460, and such tools are used to tightly fix pieces of work to engineers' machines of all kinds. When required for a lathe, three or four poppets are employed to fix one piece of work, and each poppet is fastened in one of the holes or slots in a disc chuck belonging to the lathe. While in their places, poppets are at right angles to the chuck; and after the poppets are tightly fixed, the work is put to the chuck and fastened by screwing the poppet-screws tight against the work.