DixieJack-Bugflipper is right on the Eotec-type units per his link, but some sights-referred to as "Reflex" sights have the "window" facing forward with the body closest to the shooters as in Doktor/Burris Fast Fire/TruGlo(some model-not Tubes) and others. If you are not familiar with the different types, visit a gunshow and turn some on and see which way the dot appears. My first red dot was a "fair" quality "screen forward" unit with multiple reticles. I found the images "Flared" under most conditions unless very subdued. I also discovered that after cataract surgery (that I didn't know I needed at the time) this issue disappeared. I currently have 1 Eotec, 1 Bushnell Holo-sight(Eotec Lite-warranty by Eotec if USA -made), Tacso Pro-Points, TruGlo, Bushnell's little Red Dot, and a Chinese copy of the Doktor sight by LG Outdoors. They are mounted on everything from a 7.62 Semiauto Rifle/12 ga. riot gun/223 semiauto rifles to 22LR target pistols. They have many great applications, especially for moving shots with both eyes open-the dot just seems to be "on" the target. Hope this helps a bit.