I have not researched it but most of the cylindrical fiberoptic beads are not worth a crap if they are not in a steel cage.

I use such a set up from Hi Vis on the glock and show it no mercy whatsoever.The end of the gun is scarred allover from hitting objects fast drawing with door/contact target shots. It appears they are h*llbent for strong on the Glock.

I would think that they would work great on a Double. If you have eyes that can't focus because of presbyopia(old eyes) then acquiring that white ivory dot could STILL be hard. A flaming bright red front bead would seem to be the ticket but obviously it is up to the individual to decide.

Yes, I want to put a fiberoptic front bead on my Merkel. But on a high end Double, no way!!!