It allows to mount Racktime snapit baskets on a Moustache bike carrier (tested on Samedi 28.1, I don't know for other models). There are two parts, rear and front. It is only compatible with the narrow Racktime mounting plates in order to fit within the footprint of the carrier.
It uses the threaded holes already in the carrier for the QL3 panniers.
You need 4 * M5 nuts, I used locknuts. They go in the holes on each part (see picture).
You also need 4 * M5*25mm screws, I used set screws for an invisible look.
The author marked this model as their own original creation.