I have had one of these for several years. I haven't had it mounted on anything for quite a while. It's just been sitting on a shelf in a closet. I get it out once and a while and put it on something, but it doesn't end up staying there. I mention all this so you will understand the environment it has been in. Yesterday I got it out and put it on a rifle and when I looked through the sight, I noticed in the lower right corner there was something causing a rainbow effect when looking into sunlight. My question is does the Eotech have a double pane glass arrangement? It looks like some fluid is migrating its way between the two layers. The only substance that has been in contact with the glass is some common eyeglass lens cleaner I would use. I guess it's possible I didn't get it all wiped out some time and it managed to get past some seal or gasket and get in between the layers. If this can happen so easily, I can't imagine using it in a harsh environment and having to clean it much more frequently.
I was able to grab a pick to better illustrate what I am talking about.

I was able to grab a pick to better illustrate what I am talking about.

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