Rack mount shelf with depth-adjustable rails for universal flexibility in 19" network cabinets A fixed shelf that mounts to a rack at four points is superior to a cantilever or sliding shelf 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 750 and 950 mm (29.5 to 37.4 in.). As a flexible network accessory, it universally fits Intellinet and other third-party cabinets that are 1000 mm (39.4 in.) deep.