A 19-inch rack is a standardized frame or enclosure for mounting multiple electronic equipment modules. Each module has a front panel that is 19 inches (482.6 mm) wide. The 19 inch dimension includes the edges or "ears" that protrude from each side of the equipment, allowing the module to be fastened to the rack frame with screws or bolts. Common uses include computer servers, telecommunications equipment and networking hardware, audiovisual production gear, and scientific equipment.
A standard 19-inch server rack cabinet is typically 4RU (177.8mm) to 42RU (1867mm) in height, 600 millimetres (24 in) wide, and 450mm to 1000mm deep. Typically Server rack cabinets do not come with adjustable mounting rails allowing the user to place the rails at a shorter depth if needed.