The Fixed Medium Duty Vented Rack Shelf have adjustable rails and can be installed in 19” server racks and cabinets with square, round, or threaded holes. This 20" rack shelf can rack mount server equipment weighing up to 150 lbs, including printers, desktop towers, and UPS towers, and has an adjustable mounting depth from 11” - 25”. The Fixed Medium Duty Rack Shelf can fit to 4 Post racks and can also be center or flush mounted to 2 Post racks. The rack shelf includes all installation hardware, as well as an anti-slip mat. This vented server rack shelf can also be installed upside down to allow a wider surface width of 17.7”.