Server cabinets have an internal height measured in U where 1U=44.45mm. This standardisation allows rack mounted device height requirements to be totalled. The vertical pillars in a server cabinet are normally marked from 1 and the bottom of a rack to the top U height which can be from 4U up to 47U or higher. To accommodate equipment not designed to be rack mounted, additional shelves (fixed, adjustable, and telescopic) can be added to a server cabinet. These attach as does any rack mounted devices with M5 cage nuts and bolts.
APC Netshelter Server Cabinets
APC NetShelter server rack systems include enclosed and open standard and custom full, half and wall mount rack enclosures designed for critical IT infrastructure including servers and network devices for use in IT, data centres, comms rooms, server rooms, commercial offices and industrial environments. The NetShelter range also includes Rack PDUs, NetBotz integrated environmental monitoring and surveillance, server access KVMs, rack LCD consoles, and switches to manage multiple servers and data centre containment for airflow management.

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