Module formats

For synthesizer modules to work well together in a modular system, they need to have a few basic characteristics in common, such as physical size and power supply considerations. Thus, several standard module formats have been developed over the years, and manufacturers design their modules to adhere to one or more of these standards.

1U
1U is 1.75 inch high. Unusual but used by:
 * Thomas Henry in 19-inch rack width
 * Erthenvar, Intellijel, PulpLogic as tiles

3U
3U is 5.25 inches (133.35mm) high: Used for:
 * Eurorack
 * Frac

4U
4U is 7 inches high. Used by:
 * Buchla, modules are multiples of 4.25" wide.
 * Serge, most modules are full-width panels, i.e. 17 inches to fit a rack.

5U
5U is 8.75 inches in height. Used by:
 * MOTM, 1.75 inch wide per unit.
 * MU aka Dotcom.

6U
6U is 10.5 inches high. Used by:
 * Modcan A series, panels are 2.25 inch width.
 * Wiard 300 series

Other formats
Brands which do not use standard racking formats for their modules:
 * Technosaurus
 * Mattson Mini Modular
 * Digisound 80