Had to see why this was only 3 stars - Patriot Optics Astigmanator 1x25mm Prismatic Red Dot Sight

This is an excellent optic. I didn't know that red dots were useless with my astigmatism. The reticle is crystal clear, whether I'm wearing contacts or glasses. Red AND green is great, I prefer green. I've run it on my 16" M&P Sport II and my 7" PSA 5.56 pistol. I haven't abused it, but it is well built and after 2 years, I anticipate a lifetime of use.