A Relay Rack, also known as a server or networking rack, is a customizable, fire-rated steel or aluminum frame used to store and organize networking and communications equipment such as computers and network servers.
The standard width per rack is 19 inches; however, its height can vary from a few feet tall to the ceiling. Relay racks have an open design for accessibility and airflow. The vertical frame is equipped with evenly spaced square or round holes for the insertion of screws, bolts or mounting brackets that hold the equipment in place. A relay rack is sometimes also called a two-post rack or open-bay rack.