321 (three to one) is a Eurorack Modular adapter that I designed following the Intellijel 1U panel size. The adapter lets you install 3U modules (4HP max) horizontally on the 1U row of you case. You can install one 4HP module or two 2HP modules or one 1HP and one 3HP module. Since there is no threaded strip or slide nuts underneath to secure the M3 screws, I use M3 hex nuts.
The adapter comes with 4 x M3 black screws, 4 x transparent washers and 4 x M3 black hex nuts.
**Before you buy** The adapters are made of FR-4 so there will be minor imperfections on the silk screen, or the solder mask, the holes, the cuts etc.. In fact, it’s really rare for a PCB panel not to have imperfections. This has to do with the manufacturing process and the materials that are used.