The ash wood frame is covered with a roof made of the same material to protect the birdfeed in the acrylic glass feeder from the rain. By tightening or loosening the Allen-head adjustment screws on the four corners which connect the frame with the projecting bottom plate, the distance between them can be varied: smaller for seeds and kernels of grain (so that not too much slips out at once), and a larger gap for peanuts or hazelnuts (so they don't get stuck).
A little trough has been cut into the bottom plate. The roof can simply be removed to refill the feeder with bird food or clean it. The ash wood will grey in time. As is typical for that type of wood when the feeder is new the colour may vary.