The SR42UBEXPNDNR3 houses 3000 lb of standard 19-inch rack equipment in 42U. It is an expansion model that comes without sides, doors or roof. The front and rear pairs of vertical rails have square mounting holes that are adjustable in quarter-inch increments from 4 to 37 inches. Adjustment is quick and an easy-view depth index ensures consistent rail placement without requiring time-consuming measurements. Each rack space within the enclosure is numbered for ready reference and supports tool-less button-mount 0U installation of up to four compatible PDUs and cable managers. All components of the SR42UBEXPNDNR3 are grounded to the enclosure frame. Front and rear threaded grounding points are provided for connection to the facility earth ground. To simplify deployment, the SR42UBEXPNDNR3 comes with preinstalled 3" casters that enable it to be easily maneuvered into the desired location, where it can be secured by adjusting the preinstalled levelers. Note: the casters are intended for minor position adjustments and are not designed for moving the enclosure over long distances.