Overview Tripp Lite's SmartRack SRSHELF4PSL is a standard sliding shelf for installation in rack cabinets. The SRSHELF4PSL has a 28.3 in. / 72cm depth (29.5 in. / 74.9cm including handle) and can support up to 50lbs. This fully extendable shelf can accommodate tower units, monitors and other equipment. It is designed for 4 post rack mounting and the required mounting hardware is included. Expandable mounting rails supports installation in racks with front to rear rail distances between 28 in. / 71cm minimum and 46 in. / 117cm maximum.