The HMIYADBSUDIN21 is a DIN rail adaptor from the Schneider Electric Harmony iPC range, designed specifically for the S Box PC Universal HMIBSU. It's an adaptation accessory that lets you mount that box PC onto a standard DIN rail inside a control panel — saves panel space and keeps the PC alongside the rest of the DIN-rail gear.
Mounts the HMIBSU box PC onto a DIN rail — that's its single job. No wiring, no configuration. The adaptor itself takes up one DIN-rail slot width; factor that into your panel fill when you're laying out the gland plate and terminal blocks.