are all that holds the lensboard onto the front standard of the Busch Pressman 2x3 Rangefinder camera. When looking to see what the screws were I found that they are cheese head machine screws and that all of the cheese head screws are metric. No SAE, all metric. Being that the camera is of US manufacturer could these screws be other than metric? I am still searching for the fiberglass like material that the lensboard is made of. Anyone have any experience with this material?