A manufacturer of modular synthesis equipment in the Eurorack format. Dan Green originally founded the company in 1996, in Chicago, as a manufacturer of guitar stomp box pedals (hence the original name, 4ms Pedals). The company has relocated several times and is now based in Portland, OR, USA. In 2009, the company moved into modular synthesizers, and it no longer manufactures guitar effects.
4ms is particularly known for specialized modules such as clock signal generators, audio mixing modules, and complex oscillators and filters. Some modules are available as kits, and alternate faceplates (usually black) are available for most modules.