Rack mount shelf with depth-adjustable rails for universal flexibility in 19" network cabinets A shelf with 4-point fixed rack mounting is superior to cantilever and sliding shelves in terms of stability and load capacity, but it’s usually limited to a particular installation depth. This rack mount shelf from Intellinet Network Solutions overcomes that weakness with variable rails you can adjust to depths between 350 and 550 mm (13.8 to 21.7 in.). As a flexible network accessory, it universally fits Intellinet and other third-party cabinets that are 600 mm (23.6 in.) deep.