The word “Reflex” in the term reflex sight is a reference to how the objective lens of the system essentially acts as a mirror, reflecting the targeting reticle or dot back to the eye of the shooter. This is why even though you may see a red dot, a laser is not being projected at all.

If you are looking for a reflex sight for your AR 15 rifle, it is important that you take the time to examine your options as well as look at all of the different factors that will be important in making your final decision.
Reflex or “red dot sights” come in a variety of dot patterns and colors, and they are just a couple considerations you will want to make when looking for the right one. The color of the dot is really just a matter of personal preference and technically doesn’t matter at all.
There are different colors to choose from, including green, blue, and red, all of which are fairly popular choices. Blue is a very easy color to see in bright light conditions, and red is best suited for low light situations.
It is highly recommended that you take the time to try out a couple of different color sights before deciding which one you feel most comfortable with.
The size of the dot should be large enough to where you can easily see it, but not so large as to where it will obscure your targets. Dot size is usually measured in MOA or minutes of angle.
One MOA means 1” at 100 yards, so a 5 MOA dot would mean that it covers 5” of area on a target that is 100 yards away. When it comes to a general use AR 15 sight, a MOA of about 5 is highly recommended.
The dot pattern or the reticle is another personal preference that you will need to decide on. It doesn’t really matter which pattern you choose, but there are a number of options, including crosshairs and a number of others.
There are certain sights that have adjustable reticles that allow you to quickly switch between different reticle styles, so you will want to keep that in mind when doing your research.
You will find that there are certain manufacturers that are better than others when it comes to reflex sights, and EOTech is one of them. This premier manufacturer makes Holographic Red Dot Sights that will allow you to shoot with both eyes open.
EOTech sights are known for being highly reliable and they are widely used in combat situations by the military as well as by law enforcement.
These sights also have great parallax-free optics along with completely unique rectangle-shaped lenses for a wide field of view. While the manufacturer isn’t the only factor that you should consider when shopping for one of these sights, it is definitely something you will want to keep in mind.
The more research you do into your reflex sight options, the better your chances will be of getting exactly what you need.