Knob in polished brass, designed by B&B Sweden.
30 mm in diameter.
Height 19 mm.
Dot in polished brass is made of solid brass. There is no surface treatment/coating, which means that it will oxidize and aging. Either you allow the products to age with dignity and let them be darker and get a patina, or maintain them by cleaning them quite often so that they retain their original colour.
For regular cleaning, wipe off with a little detergent/washing-up liquid.