The SR48UBEXPNDNR3 is an premium open frame rack with no sides, doors or roof. The SR48UBEXPNDNR3 houses 3000 lb of standard 19-inch rack equipment in 48U. The front and rear pairs of vertical rails have square mounting holes that are adjustable in quarter-inch increments from 4 to 37 inches. SR48UBEXPNDNR3 comes with heavy duty 3" preinstalled casters that enable it to be easily maneuvered into the desired location, where it can be secured by adjusting the preinstalled levelers.