28" Roto Shock Racks feature a depth of 29.5" from front to rear rail, with lid depths of 4.5" per lid to accommodate deeper servers. They also include a revolutionary new patented Adjustable Rail Conversion System (ARCS). This ARCS technology allows the user to adjust the rack width up to 0.5 inches on each side. Optional easy-mount adapter rails will convert the equipment mounting standard from 3/16" threaded to 7/32" through holes or square cage nut windows. The 7/32" through hole option and the 3/16" threaded are special order items. 28" 3SKB Roto Shock Racks will accommodate Dell and Compaq servers utilizing "Versa-rail" or "Rapid-rail" pull-out systems. All 3SKB Series Roto Shock Racks feature a compound hinge system that allows the lid to swing out and completely around to lie flat against the main body of the case. This also enables effortless removal/reinstallation of the lid with a simple lift motion. Both front and rear lids are designed to protrude into the base of the case approximately 1" with a unique double wall structure that makes them incredibly rigid where this intersection occurs, providing MIL-SPEC sealing characteristics with significantly fewer latches than most competitive cases. This revolutionary design allows for rapid deployment in an up-right configuration, even when stacked -- 3SKB Roto Shock Racks are the only shock racks in the marketplace today that will open front and back while stacked. The inner rack chassis is built of high strength / lightweight aluminum alloy and 11 gauge hot rolled carbon steel rack rails to EIA-310 standards, creating an H-shaped frame that provides maximum strength. Shock and vibration mitigation is accomplished with eight (8) elastomeric isolators rated for a payload range of 40 - 150 pounds in a standard configuration, and up to 300 pounds in a special order extended payload configuration allowing adequate sway space for ambient air circulation and heat dissipation. The rack rails come pre threaded for standard 10-32 hardware and mounting screws are included. Other standard features include an automatic ambient pressure relief valve and removable 4" casters. WARNING: This product can expose you to chemicals including carbon black, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov.