These styles of red dot sights are increasing in popularity, especially for use on pistols. Milling a section away at the rear of a pistol slide to mount these reflex sights increases speed on target and gives you a fast point of aim for quick follow-up shots.

On a rifle, these sights are a great low-profile option for personal defense weapon builds or AR pistol builds and can be used with riser mounts to bring the sight in-line with your iron sights to co-witness.

Open, or exposed reflex red dot sights are often battery operated and reflect their LED onto a single glass lens, ruggedly contained in a window with reinforced housing available on some models for added protection.

These sights allow virtually infinite eye relief and the single lens gives you the ability to acquire the red dot at a very wide angle of view. One of the potential downsides of sights like these is that they can be fragile if dropped or struck in exactly the wrong way.

Additionally, open-style sights leave the LED emitter open to being obstructed by dirt or debris, which would cause the optic to be totally unusable.

To combat the potential downsides of LED emitter-powered open style red dot sights, some manufacturers have designed versions that don't need batteries, replacing them with fiber-optics and Tritium. These versions use ambient light when available to power the reticle, and tritium in low-light conditions. If you never want to worry about batteries going out on you, this type of open red dot sight is a great choice. Let's take a look at some of the most popular open-style red dot sights from top optics manufacturers.

• Sig Sauer Romero 1 Reflex sight with 6 MOA Red Dot
• Trijicon RMR Type 2 with 3.25 MOA Red Dot
• Vortex Viper with 6 MOA Red Dot
• Vortex Razor with 3 MOA Red Dot
• Burris FastFire with 3 MOA Red Dot
• Primary Arms Classic Series 21mm Micro Reflex Sight - 3 MOA Dot

Red dot sights with tube assemblies are more durable than the open-style sights but the tradeoff comes with more weight and a larger footprint on your firearm than the open-style.

Functionally, this style of red dot works the same as most open style sights do, using an LED emitter. The LED is placed at the rear of the housing, reflects off the objective lens of the assembly and back to your eye.

The difference is there are two lenses and all the integral parts are contained inside the tube, which can be nitrogen-purged and water resistant up to certain thresholds. Full size red dot sights vary in size, from 30mm and 35mm tubes to microdots, but they all achieve essentially the same thing.

Red dots are spectacular at reactive shooting with both eyes open, CQB applications, and fast transitions from target to target.

The larger tubes give you some more room to find the dot as you snap your rifle up to aim. Microdots achieve an incredibly small, lightweight optic solution that is still insanely fast and superbly durable. Tube style red dot sights can be mounted on your firearm at very low heights, such as on an AK-47, or in combination with risers, cantilevered ring mounts, or other solutions to achieve lower 1/3rd co-witness or absolute co-witness on an AR-15. Trusted optics brands make some of the best red dots on the market today, so let's take a look at the most popular.

• Holosun Paralow HS503G with Primary Arms ACSS CQB Reticle
• Sig Sauer Romero 7 30mm with 2 MOA Red Dot
• Primary Arms Advanced Micro Dot with removable base and 2 MOA Red Dot
• Primary Arms Advanced 30mm with 2 MOA Red Dot
• Bushnell Trophy TRS25 25mm with 3 MOA Red Dot
• Vortex StrikeFire II 30mm with 4 MOA Red Dot
• Vortex SPARC AR Microdot with 2 MOA Red Dot
• Trijicon MRO 2.0 with 2 MOA Red Dot
• Primary Arms SLx MD-25 Rotary Knob 25mm Microdot Gen II

While these are often categorized alongside red dots and do share a passing resemblance to open style red dot housings, these types of sights do not function in the same way as the two types of red dots described above.

Holographic technology is a little difficult to explain in its entirety, but suffice it to say, these optics have holoscopic images of reticles contained in a piece of glass that is then transmitted to your eye with a laser – not an LED – sending the eye an illuminated reticle that is generally larger and more advanced than most red dots. These sights maintain the advantages of open style red dot sights like superb eye relief and fast target acquisition but can be even more durable.

For many years, one brand alone had these types of sights available for purchase. EOTech developed the technology for rifle scope applications and unveiled their first product at SHOT Show in 1996.

EOTech has long dominated the holographic sight niche of the market, but some other well-known optics manufacturers like Vortex are starting to put forth some competing products.

One thing to note about holographic sights, due to the use of lasers as opposed to the more energy-efficient LED emitters, battery life is greatly reduced in comparison to some red dot sights that can last upwards of 35,000 hours of continuous use. Here's some of the most popular holographic sight products.

• EOTech 512 with 68 MOA CQB ring and 1 MOA center dot
• EOTech EXPS2-2 with 68 MOA CQB ring with two 1 MOA dots for a 50/200 yd. zero and 7 yd CQB
• Vortex Razor AMG UH-1 with the Vortex EBR-CQB Reticle

Red Dot sights are an affordable and versatile way to vastly improve the performance of your rifle over standard AR iron sights. They allow you to get on target faster, increase your situational awareness by allowing you to effectively shoot with both eyes open, and make your follow-up shots faster and more accurate.

There's a reason red dot sights are so popular for the AR platform as well as pistols and shotguns, and it all comes down to ease of use and effective accuracy. See what all the hype is about for yourself and put a new red dot sight on your firearm today.

Get on target quickly, efficiently, and accurately when you pick up a red dot sight from Primary Arms. These sights allow the user to aim with both eyes open by displaying a red illuminated dot superimposed over-top of the target with an unmagnified field of view.

This gives the shooter total situational awareness and makes snap-shooting and reactive shots faster than iron sights alone.

The popularity of the red dot sight cannot be overstated. Red dots are the most popular AR-15 tactical optics for fast shooting at closer ranges, they're one of the most commonly used optic solutions on the modern sporting rifle, and are becoming more and more popular on handguns as well.

Red dot technology and utility has come a long way since their ancestral origins in the 20th century. The Collimator sight was a precursor to the red dot. These types of sights allowed the shooter to keep both eyes open, superimposing a dot-shaped point of aim over the target when using binocular vision.

Collimator sights were used as far back as WWI, when artillery factions used them to launch their projectiles onto enemy positions.

A different type of sight, called an Occluded Eye Gunsight (OEG), which used Tritium or fiber optics to illuminate a dot in a closed-end black tube, was most famously used in the Son Tay raid in Vietnam. These OEGs were different from Collimator sights, in that they did not allow the shooter to observe the target beyond the illuminated aiming point by looking through the tube, rather a dot inside a black circle was superimposed over the target image when using binocular vision.

An American task force attached the Single point OEG to their GAU-5A carbines' carry handles with electrical tape as they attempted to free American POWs from a Vietnamese internment camp under cover of night.

Red Dot Sights are king of sight acquisition speed because it has no eye relief, exit pupil or eye box. The red dot you see when looking through the sight is not projected forward onto the target like the laser sights, the red dot is a curved piece of glass that uses light emitted from a LED, which bounces back to your eye.

The limit of your sight picture is the field of view that you see through the sight's window. If you can see the dot at all, even in just a fraction of the scope's field of view, you can use the dot to take a decently accurate shot, if you must.

In the decades that followed as technology progressed, Aimpoint built the first electric-power, LED emitter reflex red dot and the rest is history. This breakthrough in technology utilized an energy efficient LED and reflective objective lens that transmitted the dot's image back to the shooter's eye.

Because of this breakthrough, red dots today can stay illuminated for years before needing battery replacement, and they offer most shooters a crisp, small point of aim that can be useful for accurate shots out to 100 yards or more. Since those early days, hundreds of manufacturers have innovated and designed a near-countless number of red dot style optics. With all these options to choose from, what's the best red dot for your rifle?

Most red dot sights fall into one of two categories, either tube-style or open-style. Within each category there are further variations, but that's the most basic way to distinguish between types of red dots. Check out our 2023 Red Dot Buyer's Guide for a more detailed look at the different types of red dot sights.

There are also holographic-style sights that can often fall under the umbrella term of red dot. These styles of sights use a different technology than the LED emitter red dots more commonly found on the market today, but will likely be categorized alongside red dot sights when you're shopping for your next optic.