This SmartRack 42U 4-post rack stores and organizes up to 3500 lbs (1588 kgs) of standard 19" rack equipment in 42U. The expansion model comes without sides, doors or roof. Front and rear vertical rails have square mounting holes that are adjustable in quarter-inches increments from 4 to 37". Adjustment is quick with an easy-view depth index that ensures consistent rail placement without requiring time-consuming measurements. Each rack space is numbered for ready reference and supports toolless button-mount 0U installation of 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. Heavy-duty pre-installed 3" casters allow you to roll the open frame rack into the desired location, where you can secure it by adjusting the preinstalled levelers (the casters are intended for minor position adjustments and are not designed for moving the enclosure over long distances).