Sig Sauer is an established and recognized optics manufacturer, and Holosun has wowed the masses with quality and value.
With personal experience using both of these red dots, I compile my comparisons in this Sig Sauer Romeo 5 VS Holosun HS403B review.
I set a criterion to analogize cost, motion sensor performance, battery life, and more to determine which is best for you!
Quick Comparison Overview & Table
The Holosun HS403B and the Romeo 5 red dot sights are similar in many ways but are slightly different in cost, illumination settings, battery life, mounting heights, and motion sensor adjustability. The slim margins I compare may highlight the differences in determining which is right for you.
If you want to cover either of these red dot sights in more detail, you can read my full hands-on field test reviews here:
|Features||Sig Sauer Romeo 5||Holosun HS403B|
|Price Range||Under $150||Under $160|
|Dot Size||2 MOA||2 MOA|
|Adjustment Value||0.5 MOA||0.5 MOA|
|Illumination Settings||8 DL / 2 NV||10 DL / 2 NV|
|Battery Life||40,000+ hours||50,000+ hours|
|Battery Type & Location||CR2032 – side-loading||CR2032 – side-loading|
|Mounts||Absolute co-witness & low-profile mounts||Lower 1/3 co-witness & low-profile mounts|
|Dimensions||2.4 x 1.5 x 1.5”||2.45 x 1.43 x 1.6”|
|Weight||5.1 oz||2.82 oz|
|Lens Caps||Rubber bikini||Rubber bikini|
|Special Features||MOTAC||Shake Awake|
Feature Comparisons of the Sig Sauer Romeo 5 VS Holosun HS403B
In general, the Romeo 5 and the Holosun HS403B are very competitive in price. They’re both considered among the best budget red dot sights, and they top the charts when it comes to value and quality performance.
The MSRP retail price is around $200, but they’re often close to and under $150 at street prices. On average though, the Romeo 5 is cheaper than the Holosun red dot.
Winner: Sig Sauer Romeo 5
In general, the configuration is my definition for the magnification and objective lens size. In this case, both the Romeo 5 and the Holosun HS403B have identical configurations of 1x20, i.e., 1x magnification and a 20mm objective lens aperture.
This is a common configuration for a fully enclosed micro reflex red dot sight. They are different in design to heads-up (HUD) red dot sights, like the CVLife or the EOTech EXPS3, and pistol red dots, like the Leupold DPP, that have windows and frames.
Neither the Holosun or the Sig has an advantage over the other when it comes to configuration.
A 2 MOA dot is a standard dot size for both full-size and micro red dot sights. It’s good for CQB and long range to around 150 yards and maybe 200 yards if needed. The Holosun red dot and the Sig Sauer Romeo 5 have 2 MOA red dots with 2” subtension at 100 yards.
Does the Holosun have a circle dot reticle?
Though many Holosun red dot sights offer the option of selectable reticles or just the 65 MOA circle with a 2 MOA dot, like the field-tested HS510C, the HS403B does not have it. It features only a 2 MOA dot reticle.
Most red dots have 1 MOA adjustments, but some will have 0.5 MOA adjustments. This allows for a little bit more accuracy than a 1 MOA red dot. This can be indicative of a top-tier or costlier sight and may be why the Romeo 5 and Holosun HS403B are more expensive than other budget red dot sights.
When it came to sighting-in them in, both were easy to do. I got on paper out of the box with both sights, and it’s fair to say that it was a routine experience with groupings out to 100 yards.
Both are audible and tactile in feel, however, the Romeo 5 is a little easier to adjust with the cap versus the Holosun. Both come with a multi-tool to make adjustments somewhat more convenient, but the caps have slot ridges to serve as the tool.
For more on how to zero a red dot sight, check out my step-by-step instructions.
Red dot sights either have exposed or capped turrets. I personally prefer exposed turrets because it means you don’t need to deal with caps or snagging, but I also like that the caps usually serve as the tool to make adjustments. In this case, both red dot sights are capped.
Now I do have an opinion on which caps I preferred. The Romeo 5 elevation turret cap is slightly recessed into the body on one side. It makes it tedious to get that cap off. Secondly, the windage turret is very close to the battery compartment, again, making that cap tedious to get off.
The Holosun elevation cap is slightly recessed into the body but are far easier for me to uncap. Given that there is no bulging battery compartment on the side, it is less of an issue to remove the caps.
Additionally, both red dot sights have reference markings inside the caps indicating which direction to make adjustments. The Romeo also has UP and R markings complete with arrows on the body of the red dot – just in case you needed an extra reminder.
Given that I find the caps on the Holosun easier to grip due to the design, I’m inclined to prefer the Holosun.
Winner: Holosun HS403B
Overall, the Holosun HS403B and the Sig Sauer Romeo 5 perform very similarly in terms of illumination and dot visibility. Both have as natural color fidelity you can have from a red dot, and very little internal reflections.
The Romeo 5 has 8 daylight settings and 2 dedicated for use with night vision gear. The Holosun has 10 daylight settings with 2 night vision compatible settings.
I found that both are highly visible in daylight conditions at max brightness, enough so that I deem them daylight bright. However, neither are ‘nuclear’ bright on white or reflective targets. Though extremely faint against these types of surfaces, it would take considerable time to use it in these tremendously harsh conditions. In all other conditions such as at an outdoor range, in urban environments, and in the timer, I have no complaints.
The Holosun has two more daylight settings than the Romeo 5, but I still felt like the Romeo 5 was slightly brighter at max versus the Holosun at max - regardless of how many settings there were. On paper, this would normally go to the HS403B but to the very slight difference in what I saw with my eyes, I'm giving it to the Romeo 5.
Winner: Sig Sauer Romeo 5
It’s either buttons or an illumination knob/dial that you’ll get with a red dot sight. The Sig Romeo 5 and the Holosun red dot both have buttons to control the illumination. They look to be exactly the same size and are flush with the body of the red dot.
The buttons are not easily compatible with gloves in my opinion. Due to the small size and recessed design, they are hard to feel with gloves on. However, this is a non-issue without gloves.
As a side note: I am partial to illumination knobs/dials on red dot sights. Well-made ones are incredibly convenient to use. You can see the setting you’re on, rig an intermittent ‘off’ position, rotate past '0' in both directions, and they’re easy to turn without unintentional rotations. Check out the STNGR Axiom II that fits my description to a T!
In this comparison, you almost can't tell the buttons apart from either model, and once again, neither red dot offered something to one-up the other, so it’s a tie.
As far as marketing claims go, the Holosun HS403B has the longest battery runtime of 50,000 hours versus the 40,000 of the Sig Sauer Romeo 5. The extra 10,000 hours awards the Holosun the longest-lasting red dot sight between the two.
These high-performing and low power consumption red dot sights are evidence of modern-day advancements from LED and battery technologies to optical system improvements.
Though both the Sig and the Holosun are incredibly long-lasting red dots, I’m giving the longer battery life award to the Holosun.
Winner: Holosun HS403B
Battery Type & Location
Most red dot sights will require a CR2032 battery. There are red dots that are the exception to the rule like the field-tested Sig Romeo MSR that takes a CR1632 battery. In comparison, the CR2032 is superior. The Romeo 5 and the Holosun HS403B come with a CR2032 battery as the power source.
If my judgement parameters were just battery type alone, it would be a tie. However, the battery location presents an interesting user experience and discussion (mostly a vent).
The Holosun has a compartment tray on the side of the body that houses the battery. It’s convenient right? And there’s no protruding bulge on the side. Overall, the Holosun looks sleek and trim. However, I hate the tray.
Though I like the concept of the tray, the screws are tiny, T5 (I’m sure). I’m also sure that I’m going to strip these screws at some point. Fortunately, Holosun includes an extra battery tray complete with two tiny screws that are needed. Unfortunately, the small screws made things tedious. It’s not always a smooth experience to get in and get out of there. Given that it has an industry-best battery runtime, I’ll rarely have to deal with it.
You can see the big knob on the Romeo 5 and immediately want to identify it as an illumination knob, but its sole purpose is to house the battery. I’ve already started stripping away the finish on the slot to tighten and loosen the battery compartment knob. At least it’s straightforward, and it’s far easier to deal with than the battery tray on the Holosun.
Winner: Sig Sauer Romeo 5
The Romeo 5 and the Holosun come with riser mounts and low-profile mounts in the box. The Holosun HS403B riser mount has a height set for a lower 1/3 co-witness. The Romeo 5 riser mount is set for an absolute co-witness. The Holosun is slightly taller than the Romeo 5.
This matters if you run irons (BUIS) on your AR and plan to use your sights if there is red dot failure. It will also matter if you’re pairing it with a magnifier. Spacers may be needed or removed to align the two optics.
They are both direct-to-rail mounts meaning that they’re directly tightened to the rail via a tool (usually a Torx wrench) to provide tension to clamp the keeper and crossbolt to the rail. Both sights require a T10 Torx wrench to mount the sight to the rail, and they are included in the box.
Neither come with a quick release mount, so having back up sights on the rail is a good idea in case of red dot failure as removing the red dot will take time.
In general, both red dot sights are very similar in dimensions. The HS403B comes in at 2.4 x 1.4 x 1.6” while the Romeo 5 comes in at 2.4 x 1.5 x 1.5”. These dimensions are for the red dot sight body only and does not include the mount. I call this a wash between the two sights in terms of size.
When it comes to weight, the Romeo 5 weighs 5.1 oz while Holosun states that the HS403B weighs 2.82 oz. I haven’t put either to the scale as I did suspect this was the weight of the Holosun without the mount. However, in the hand, the HS403B does feel and weigh significantly lighter than the Romeo 5.
Winner: Holosun HS403B
Overall, the Sig Sauer Romeo 5 and the Holosun HS403B are similar in terms of build quality. They’re made from aluminum but have a different finish that may set them apart. Though both have taken on superficial scratches, it’s nothing a good clean can’t get rid of.
The Sig Romeo has an anodized matte black finish that is good for anti-reflectivity benefits, but it also means that it takes on some scratches. Mine are superficial and should be easy to remove. Most optics these days have this anodized matte black finish.
The Holosun has a MAO (Micro-arc Oxidation) finish. From the little that I know, a metal oxide coating by MAO techniques is said to be superior to anodization. While it may be more corrosion resistant, it has taken on superficial scuffs too.
Either way, both have held up well and similarly. I guess only time and usage will tell how they differ when it comes to wear and tear.
Both are waterproof but whereas the Romeo 5 is IPX7 rated, the Holosun is IP67 rated – meaning that it’s also rated for dust.
I actually field-tested both the Holosun and the Sig red dots in the same storm. I got caught out in the rain, removed the sights from their rifles and then left them out exposed to the downpour. Though water penetrated every nook and cranny, neither red dot exhibited internal fogging or water on the inside. Both perform exceptionally to date.
Once again, both sights share the same country of manufacture: China. Holosun is more upfront about it having it stamped on the mounts and it’s stated obviously on the box. Sig Sauer declares that it’s assembled in China in small print on the box.
Since the Holosun has a fancy finish and is also dust-rated, it takes the cake on build quality.
Winner: Holosun HS403B
Generally, rubber bikini caps are the standard caps that are included with red dot sights, and the Romeo 5 and the HS403B follow that standard. However, they did add a touch of their own flair to the caps.
The Holosun has standard circular caps with the Holosun brand name across the center of both caps. They're stiff and fit snugly to the ocular and objective bells.
The Romeo 5 adds even more style with its custom cap design that fits perfectly with the custom cut ocular and objective bells. I give it points for originality, and it looks great. Even though I’m sure I’m going to lose both sets of caps or the bands will succumb to snapping at some point, I can’t deny the visual appeal of the Sig caps.
Winner: Sig Sauer Romeo 5
The Holosun HS403B and the Sig Sauer Romeo 5 share more than just configuration, dot size, and button operation. They also have a motion sensor feature. Holosun’s motion sensor tech is called Shake Awake while Sig Sauer’s is called MOTAC – short for Motion Activated Illumination.
This special feature is beneficial for tactical professions and civilians for home defense applications. A built-in sensor senses movement and inactivity and activates or auto sleeps the illumination accordingly. The difference here lies in the time it takes until that red dot automatically goes into sleep mode.
The Romeo 5 has a very short timer of 120 seconds (2 minutes). The Holosun has an adjustable timer from 0-12 hours with the default setting of 8 hours.
Obviously, there are pros and cons to both sleep timers. The Sig can’t be adjusted for a different sleep timer while the Holosun is limited to adjustments in hours and not minutes.
Since the Holosun allows for some adjustability, and it still has a longer battery life with the longer sleep timer, it outdoes the Sig Romeo 5’s MOTAC.
Winner: Holosun HS403B
Who is the Sig Sauer Romeo 5 Best Suited To?
The Sig Sauer Romeo 5 is best suited to duty rifles, SHTF and home defense civilians, and perhaps similar tactical applications. It’s set for an absolute co-witness for those who run sights. It's an affordable but quality red dot sight that comes with the Electro-Optics Infinite Guarantee.
The warranty looks to be split in two, and it’s assumed that the electronics, respectively the LED illumination system, is only warrantied for five years.
Though the Romeo 5 is similar to the Holosun HS403B in operation, it has a significantly shorter sleep timer, a highly visible dot, a convenient and easy-to-use battery compartment, and it’s cheaper. Plus, I really like the custom bikini caps!
Who is the Holosun HS403B Best Suited To?
The Holosun HS403B is best suited to applications where the Shake Awake feature is valued. This includes home defense and law enforcement. Given that the timer can be turned off for a continuous-on function, it is also a viable red dot sight for hunters.
It’s warrantied for life with conditions. It’s valid only to the original purchaser, and the LED illumination system is warrantied for 10 years from the date of manufacture. If it’s used for law enforcement or military applications, the warranty is only valid for 3 years.
I really like the Shake Awake, highly visible dot, and lower 1/3 co-witness mount, but I’m not in a hurry to deal with the battery compartment any time soon. With that aside, the Holosun is a high-performing red dot with a lot to offer. It’s a solid optic that’s best for those looking to get the most out of their buy.
On average, the Sig Sauer Romeo 5 is a 1x red dot sight that is often used inside 100 yards. Long range equates to 100-300 yards with a red dot sight. Getting out that far is easier done when paired with a red dot magnifier.
MOTAC and Shake Awake use a motion sensor to activate the illumination when it senses movement. The vibrations felt in a moving vehicle will activate the dots in the Sig Sauer Romeo 5 and the Holosun HS403B. From field-testing, the red dots are very sensitive.
Image by Tina Fa'apoi (Own Work) for Target Tamers
The Sig Romeo 5 and the Holosun HS403B have the Aimpoint Micro Standard footprint. It’s the T1 footprint and is very common among enclosed micro red dot sights. I was able to successfully switch mounts to a quick release mount that came with the STNGR Axiom II just to try it.
The Shake Awake feature in the Holosun HS403B can be deactivated completely to provide continuous-on and manual off/on benefits. It is adjustable from 0-12 hours but cannot be adjusted for minutes.
Press the + button for 3 seconds and press the – button to decrease the timer. The number of LED blinks indicates the hour setting. Zero blinks indicate that Shake Awake is off. Press the + button for 3 seconds to save the setting.
In general, enclosed micro red dot sights are too big to be mounted to a Glock or other handguns. Red dot sights for pistols have heads-up displays (HUD) and are even smaller in size. The Romeo 5 and the Holosun red dot are intended for mounting to rifles and carbines with a Picatinny rail.
Holosun HS403B & Sig Sauer Romeo 5 red dots mounted to rifles & Holosun pistol red dot mounted to Glock - Image by Tina Fa'apoi (Own Work) for Target Tamers
Holosun HS403B VS Sig Sauer Romeo 5: Which is Best For You?
The primary differences between the Holosun HS403B and the Sig Sauer Romeo 5 include the motion sensor sleep timer, weight, mounting height, and battery life and location. Though very similar in all other aspects, the Romeo 5 is the cheapest red dot sight between them.
Between comparing the Sig Sauer Romeo 5 VS Holosun HS403B, both will perform near alike. Determining which is best for you may come down to slim differences that sets them apart from each other.
At the end of the day, personal preference wins out, but I don’t think you can go wrong with either one.