Enclosed vs Open Red Dot Sights: Which Should You Choose?

Choose an enclosed red dot if the gun will be used outdoors in wet, muddy or dusty conditions. The sealed emitter can't be blanked by rain, lint or grit. Choose an open red dot for dry range, competition and budget builds, where a lower, lighter and cheaper sight matters more than weather sealing. In British weather, most field guns are better off enclosed.

The weight penalty is smaller than people expect. On Holosun's own figures, the enclosed full-size EPS is actually lighter than the open 507C X2.

What's the difference?

An open-emitter red dot has an LED sitting exposed at the back of the sight, shining forward onto a single angled lens that reflects the dot back to your eye. An enclosed-emitter red dot puts the LED inside a sealed housing with glass at both the front and the rear, like a small box or tube. Nothing can land between the emitter and the lens.

Both are reflex sights, and both show you a dot. The difference is what happens when the weather or your kit bag gets involved.

Open-emitter red dots

Open sights are usually lower, often lighter and cheaper, and give a large, uncluttered view. The drawback is the exposed emitter. A raindrop, a snowflake, a smear of mud or a bit of lint from a gun slip can sit on the LED and block or distort the dot until you wipe it off.

Good for: indoor ranges, competition, dry-weather rifles, airsoft and budget builds.
Examples we stock: the Holosun HS507C X2 and Trijicon RMR Type 2 for pistols, and the Holosun HS510C, which Holosun describes as an open reflex, for rifles and shotguns.

Enclosed-emitter red dots

An enclosed red dot seals the whole optical path, so the dot keeps working through rain, dust and debris. That's why enclosed sights are the sensible default for field use, practical shotgun and any rifle that lives in a wet slip. You get a slightly taller body and, usually, a higher price. The IP rating tells you how well the sealing is tested. Holosun lists the EPS family at IPX8.

Good for: all-weather, outdoor and hard-use setups.
Pistol examples: the Holosun EPS Carry for slim slides, the full-size Holosun EPS, the titanium Holosun HE509T X2, the Trijicon RCR on the RMR footprint, and the Burris FastFire E on the ACRO footprint.
Rifle and shotgun examples: EOTech's holographic sights, which have glass at both ends of a hooded window, plus the rifle-sized options in the enclosed collection.

How the numbers compare

All figures are from Holosun's product pages. In the Holosun range, then, going enclosed costs very little in weight, window or battery life. The real differences are height, price and how much cleaning you'll do in the field.

Which should you choose?

• Choose enclosed for any gun used outdoors in British conditions: field rifles, practical shotgun, wet ranges, or anything carried in a slip.
• Choose open for indoor ranges, dry-weather competition and budget-conscious builds where the lowest height and price matter most.
• Either way, check the footprint first. Our pistol footprint chart lists which enclosed and open sights fit which cut.

Setting up a pistol? See our best pistol red dot sights guide, the EPS vs EPS Carry vs EPS CORE comparison, or the compact slim-slide red dot guide.

Frequently asked questions

Are enclosed red dots worth it?

For outdoor and field use, yes. The sealed emitter keeps the dot visible in rain, sleet and mud, where an open emitter can be blocked. For dry indoor range use, an open dot is fine and usually cheaper.

Do open red dots fail in the rain?

The electronics don't fail, but water or debris on the exposed emitter can block or distort the dot until you clear it. Enclosed sights avoid that.

Is an enclosed red dot heavier?

Not necessarily. Holosun lists the enclosed EPS at 1.4 oz and the open 507C X2 at 1.5 oz. On the slim models, the EPS Carry is 0.23 oz heavier than the 507K X2.

Can I fit an enclosed sight to an open-sight slide cut?

If the footprint matches, yes. The Trijicon RCR uses the same RMR footprint as the open RMR, and Holosun includes plates that put the EPS onto RMR cuts and the EPS Carry onto RMSc cuts.