4POSTRAILKIT1U is an adjustable rack-mount shelving system that supports heavy UPS systems, as well as other pieces of networking or power protection equipment. 4-post expandable mounting rails offer front to rear support for equipment with 17.5-inch-wide rectangular chassis. Rails adjust to any setting between 20.5 and 36 inches. Includes mounting hardware compatible with square-hole racks. Supports up to 150 pounds (68 kilograms).