An Electrical utility box is typically a rectangular, open-faced box mounted in a wall. It serves to house an electrical device, such as an electrical receptacle or switch or a GFI (ground fault interrupter) .... The mounting boss has a bore configured to receive a fastener that fastens the electrical device to the box.
Utility boxes are used for convenience outlets, switch boxes or small junction boxes. They are popular for exposed work applications (surface mounted wiring). Raised ground screw provides easier access and prevents the ground screw from protruding beyond the bottom of the box when tightened.
There are round, square, retangular, shallow, weatherproof, and extension boxes. Electrical boxes come in plastic and metal varieties. Plastic boxes are non-conductive and are relatively inexpensive. They come in different styles that either nail on or are the cut-in variety