All vices are designed either to hold work which is to be worked on, or to hold specialized tools such as turns, mandrils, stakes, etc. A bench vice is one which is either clamped or screwed to the top surface or edge of the bench. Most vices today have jaws which, by meanas of a screw, open in such a way as to keep them always parallel, the jaws being part of cast- or wrought-iron members, one of which slides through the other. Many older bench vices had pivoted jaws which necessarily opened at an angle and were therefore limited in their gripping action. A bench vice is sometimes fitted with a stand secured to the bench, enabling the vice to be swivelled to a desired angle, and some large vices have a leg or pole extending to the floor for extra stability when doing heavy work.