The EOTech sights are a two eye open sight.......means that you do not close one eye while firing at a target......allows you to be able to keep an eye out for other targets coming into view.........it also allows one to aquire your target faster because you do not have to align up the front & rear sight....the holo does that for you at any angle looking through the sight...as long as the target can be seen in the view finder you can put the target dot/circle (depending on you model you have) on the target and hit it every time......there is a reason why it costs so much more and why the "regular" GI in the current combat zones are buying them for themselves (US military so far does not supply them for the front line troops...just special OPS type units)...because they save lives........Some EOTech sights also allow one to sight in on targets at different distances at the same time........as they say "you get what you pay for"........But do not confuse a Red Dot or a Holo sight with a long distance scope........red dots & holos are for for close in work (within a couple hundred yards or so I would think). My wife works at EOTech and I just purchased one (512) for my HD Shotgun and it is really amazing how well it works.......