whatever, they are fastened onto the lens in some manner, I was explaining the principle of the blue dot. I have no idea how they are actually installed as I personally have never used them, just looked at them. Had a roomate once in the navy that was all into lowriders, that is actually where I first learned of blue dots. 4 or 5 times a day I learned of blue dots, along with something about a binks agitator cup spray gun to get the best pearl paint job.
