From DT Online
Engineer's Vices are very useful for holding work whilst sawing, drilling, bending for example. These vices have metal jaws and so great care must be taken if used together with any sharp edge woodworking tools to avoid blunting them.
Features and Applications
Clamp-on vices are very suitable for general small-scale work.
Fixed Engineer's Vices typically have 100mm wide serrated jaws which will mark soft metals and other materials. Softer clip-on or magnetic vice jaws can be used to protect work or the fixed jaws can be replaced with smooth ones for lighter work.
Safety Point! The handle of a large fixed vice can be heavy and trap fingers as it slides down - place rubber rings under the ends to avoid this.