The heavy duty rack shelf is compatible with 19" server racks from manufacturers such as Dell, HP and IBM. Heavy duty rack shelves can be installed into racks with square, round, or threaded holes. Rack mount equipment weighing up to an astonishing 900 lbs (409.9 kgs) can be installed using a heavy duty rack shelf. The rack shelf is 28" (711 mm) deep and can be installed into server racks with installation depths up to 31.5" (800 mm).