Today I have found this hat in a "second hand" shop for about 1 $.
It has no trace of any insignia or stamps. Also there are two little holes as marks on each side on the places where suppоse to be ventilation holes. As you can see there are no typical edges on the cut of the ridge on both sides.
So is the the next "unsolved" case , or desperаte lost cause ... or just some reproductor's first attempt ?