This is a home made winding crank knob for Bolex cameras. You get one, the other ones are shown for demonstration purposes. The parts were made using black casting polyurethane which is very durable. Since the parts were cast they are going to have some imperfections at the bottom, but it's not terribly bad and that part goes against a washer so it's not visible.
This knobs were made using the knob of my Rex 4 as master. I have noticed newer models like the Rex 5 use longer knobs, so please do your research before buying the part. You can measure the shaft or the part you have and compare the numbers..
As you can see on the pics the length of the shaft that receives the knob is 14mm and the diameter is 4mm. You can measure the shaft of the winding crank of your camera to make sure it works before buying. No returns please.
Thanks for looking.