I lost one of mine quite awhile back and replaced it with a SS 6mm cap screw until I could figure out where to buy a replacement. I paid like $20 plus shipping for a pair when I did find them.I am looking for a bracket knob for a newer Simrad unit.
I had one fall off and out of the skiff.
If anyone has a flush mount, I would like to buy your useless knob.
You could use a couple of these for much less.