Eurorack

Euro is a modular synthesizer format. The height of Euro format synthesizer modules is equal to three vertical units in a standard 19" equipment rack. This standard height is called "3U". Euro format modules typically use 3.5mm (1/8") connectors and plugs for patching.

A list of the depth of Eurorack modules (from this thread):

Livewire  Frequensteiner - 1.50" (38.1mm) Dual Cyclotron - 2.25" (57.15mm)

Plan B  Model 28 - 2.50" (63.5mm) Model 15 - 1.75" (44.45mm) (MKII, MKI is much deeper) Model 14 - 3.75" (95.25mm)

The Harvestman  Tyme Sefari - 2.00" (50.8mm) Malgorithm - 1.50" (38.1mm)

Doepfer  The Doepfer module depths can be found at their "planner" Excel file: http://www.doepfer.de/pub/a100_sys.xls (thanks fits)

Manufacturers of Euro format modules include the following:

Analogue Solutions

Analogue Systems

Cwejman

Doepfer

Livewire

Malekko

Makenoise

Harvestman