Terminal and junction boxes are used to house electrical components and facilitate wiring. They are T-shaped or rectangular, made from a variety of materials, and available in many different sizes, sealing configurations and mounting styles. Length, width, and height are important dimensions. Inside length, inside width, and inside height are also important considerations. Because some terminal and junction boxes can be mounted in several different ways, suppliers recommend viewing product pictures or diagrams to determine which dimensions refers to length and which dimensions refer to width. For standard enclosures, the length or height is measured parallel to the hinge axis. For products with a screw-on or non-hinged cover, the length is the longer of the two dimensions. For enclosures that are rated by the National Electrical Manufacturers Association (NEMA), the width is perpendicular to the hinge axis and the depth is the distance from the opening to the back.