In eurorack modular systems the modules are mounted to the rails. The length of these rails is typically standardized to HP widths (1 HP = 5.04mm). Note that eurorack rails typically use M3 screws while the industry standard in Germany is M2.5.
Note that in addition to the (two) rails you will need:
- screws that fit the nuts
- square nuts that fit your rails (or something [like this](https://www.reichelt.de/Baugruppentraeger/BGT-384-2/3/index.html?ACTION=3&LA=446&ARTICLE=50392&GROUPID=7756&artnr=BGT+384-2&SEARCH=bgt))
- screws to screw into the side of your rails
## Sources
- BGT ("Baugruppenträger") on reichelt. For example [this](https://www.reichelt.de/Baugruppentraeger/BGT-GB-29L/3/index.html?ACTION=3&LA=446&ARTICLE=50387&GROUPID=7756&artnr=BGT+GB+29L&SEARCH=bgt)
- Stefan Burbulla of Clicks & Clocks sells already assembled rails/frames. Have a look [here](http://clicksclocks.de/20170114_ClicksClocks_price_list_web.pdf). You have to order by mail.
