This is an adjustable mount for the dock for a Euclid Z probe, to fit on the Seckit SK-Tank. The bracket attaches to the underside of a Y brace*, the tray attaches to the bracket, and the dock itself attaches to the tray. The dock shown is the stock one downloadable from the Euclid Github; heatset an M3 nut into the top hole and then use an M3 screw to attach it.
*I recommend the back of the right Y brace (on the +X side), so that when you home X and Y, the carriage goes away from the dock, minimizing any risk of collision or accidental probe pickup.
The author hasn't provided the model origin yet.