> >> 1U=4.5cm > > Approximately :) at least in poland it's said that. i must check in my 12U rack ;) > > At least in the US, 1U = 1.75 inches = 4.445 cm, so an 18cm case > will not quite fit into 4U. Perhaps metric racks are different. well it will with slight amount of pressure ;) to compensate this 2.8mm