DIN rail

A DIN rail is a metal rail of a standard type widely used for mounting circuit breakers and industrial control equipment inside equipment racks. These products are typically made from cold rolled carbon steel sheet with a zinc-plated or chromated bright surface finish. The term derives from the original specifications published by Deutsches Institut für Normung (DIN) in Germany, which have since been adopted as European (EN) and international (IEC) standards.

There are three major types of DIN rail:

This 35-mm wide rail is widely used to mount circuit breakers. The EN 50022 standard specifies both a 7.5 mm (shown above) and a 15 mm deep version, which are officially designated

Some manufacturers catalogs also use the terms Top hat section / Type O / Type Omega (Ω).

It is known as the TS35 rail in the USA.

These rails are symmetrical within the tolerances given. There are four popular C section rails, C20, C30, C40 and C50. The number suffix corresponds to the overall vertical length of the rail.

G-type rail (according to EN 50035, BS 5825, DIN 46277-1).

In addition to the popular 35 mm × 7.5 mm top-hat rail (EN 50022, BS 5584, DIN 46277-3), several less widely used types of mounting rails have also been standardized:

...
Wikipedia