Tripp Lite's 4POSTRAILKIT adjustable rackmount shelf system supports heavy UPS systems in 4 post rackmount applications. Includes one pair of expandable "L bracket" mounting rails to offer front-to-rear support of rackmount UPS systems. Pair of expandable "L brackets" adjust to any setting between 20.5 and 36 inches. Includes mounting hardware compatible with square-hole racks. Set of temporary placement pegs enables simple single-person installation by allowing the rails to be held in place while attachment hardware is installed. Also compatible with other heavy pieces of networking or power protection equipment with 17.5 inch wide rectangular chassis. Supports up to 250 lbs.