The SR45UBEXPNDNR3 is an expansion model with no sides, doors or roof. An expansion model is useful when baying together multiple enclosures. Its integrated baying tabs make it easy to combine multiple enclosures in rows for data center applications.The SR45UBEXPNDNR3 houses 3000 lb of standard 19-inch rack equipment in 45U. 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 SR45UBEXPNDNR3 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 SR45UBEXPNDNR3 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. Note: the casters are intended for minor position adjustments and are not designed for moving the enclosure over long distances.