I have Glock (Trijicon) OEM sights on a G19 that have discernibly dimmed, but are not useless, after at least sixteen years, maybe longer. Otherwise, I have a bunch of XS Sight Systems product, which use Trijicon-made capsules, I think. I like the XS "Big Dot" front on j-frames, and their "Express" sights on any SD gun that will accommodate them. Their factory rep told me that they have some sort of generous replacement policy for sights that have reached the end of their useful life, but I don't see that published anywhere.