The jaws of a hand-held vice are located at one end of a pair of handles, which are then attached together at the other end, similarly to a pair of tongs.
The face of each jaw is textured in order to grip a workpiece, so that it does not slip out of the jaws.
Screw
The screw is the part that is in control of opening and closing the jaws of the vice. The length of this screw determines how wide the jaws of the vice can be opened.
The body of the screw is threaded so that it remains in place once the vice is closed around a workpiece.
The screw is tightened by a wing nut.
Additional features
Pin hole
Some models of hand-held vice have a pin hole in the jaws, in order to grip objects of a small diameter, such as metal wire.
Spring-action
Some models can also have a spring-action to keep the jaws open. This works by separating the handles by pushing them out in opposite directions. This is a useful feature as it keeps the jaws from inconveniently coming together when attempting to insert a workpiece.