19” relay racks are the most basic type of rack available. They are called relay racks because they were predominately used in telephone company offices where thousands of switching relays were mounted.
There are two standard size racks available, 19” and 23”. The 19” is the most common size. Almost all telecommunications equipment mounts into a 19” rack. The 23” rack is mostly used in the computer industry.
The 19” relay rack is available in many different sizes for holding different amounts of equipment. Rack mount equipment is fastened to vertical rails spaced 19” apart. The open frame design allows easy access to all sides of the equipment.