The SR42UBMDEXPND is a 42U SmartRack enclosure with NO doors and NO side panels. The 'EXP' version is an expansion model used when several cabinets are bayed together make it easy to combine multiple enclosures in rows for data center applications. This enclosure is also compatible with hot-aisle/cold-aisle configurations. The SR42UBMDEXPND houses 3000 lb of standard 19-inch rack equipment in 42U. Its front and rear pairs of vertical rails have square mounting holes that are adjustable in quarter-inch increments from 4 to 31 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. Two of the adjustable vertical mounting rails support toolless button-mount 0U installation of up to four compatible PDUs and cable managers. This feature makes it easier to route cabling to rack equipment and reduces cord clutter.