The 19" 12U Studio Rack Cabinet by Gear4music.com provides 12U worth of 19" rack space.Photo: https://www.gear4music.com/Recor...
A standard equipment sizing format allowing products to be mounted between vertical rails in standardised equipment bays (racks).
A 'U' is a unit of measurement used to denote vertical space in 19" (server) racks. Each 'U' is equivalent to 1.75 inches or 4.445 centimetres. Rack-mounted devices are sized in units of 'U's, with devices requiring 1U of space, 2U's for devices that require two units, and so on.