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Holosun Paralow HS403B

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Holosun Paralow HS403B Details

About the Paralow series

Paralow is one of the red dot sight series made by Holosun. On the outside, these small tube sights are very familiar to the Micro red dot sights made by the famous Swedish red dot sight manufacturing company. The illumination is powered by a CR2032 battery. The click value for the elevation and windage adjustments is 0.5 MOA. These durable red dot sights feature a single-piece housing made out of aluminum. Altogether, there are 12 illumination intensity levels to choose from, 2 of which are NVD compatible. The battery life is 50.000 hours. These are compact but not as small as an open reflex sight.

About the model family

The 403 is one of the model families in the Paralow series. The first number '4' in its name suggests that it features a 2 MOA dot (the user cannot switch to the circle dot reticle as with models that start with number '5'). The second number '0' implies that the product comes with standard accessories (without honeycomb filter, quick-release mount and flip-up lens covers).

About the product (HS 403 B)

HS403B is a red dot sight of the Paralow series.

The letter 'B' means that the battery compartment is on the right side of the device in the form of a battery tray. Also, it doesn't run on solar power (no solar panel on top), which is why this model has buttons for the regulation of illumination intensity on the top instead of on the side.

It is a great choice not only for standard hunting rifles and AR-rifles but also shotguns, pistols, air rifles, and crossbows.

The product features the ShakeAwake function. When left powered on, the device will go from 'active mode' to 'sleep mode' after a while to prevent unnecessary battery drain. Once moved, it will power back on immediately.

Thanks to Holosun's LED technology, the battery in this small, compact red dot sight lasts up to 50.000 hours.

 Main features:

  • 2 MOA dot

  • comes with a low mount and a high mount for lower third co-witness on standard AR platforms

  • Shake Awake

  • same mounting platform as Aimpoint Micro devices

  • 12 illumination intensity levels, 2 of them are NVD compatible

  • Parallax free

  • 50.000 hours of battery life

  • the battery compartment on the right side of the device in the form of a battery tray

Mounting details

These small tube sights come with a high mount for an AR platform (lower 1/3 co-witness) and a low mount for other mounting purposes (such as mounting on a rifle). All models in the Paralow series except the ones with the letter 'A' in their name have the same mounting platform as the Aimpoint Micro devices.


The warranty is 5 years on the material and 3 years on the electronics.

For more information regarding the Holosun symbols, check our blog post.

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Holosun Paralow HS403B Specifications

Dot sight seriesHolosun Paralow
Made inChina
In production since-
WarrantyHolosun Classic - 5 years (Housing) / 3 years (Electronics)
Click Value 14mm/100m - 1/2MOA
Windage - mrad. 0mrad
Windage - MOA.0MOA
ReticleDot Illuminated
Reticle position 1. focal plane - FFP
Reticle illumination Yes
Illumination color Red
Usable at daytime Yes
Automatic Turn Off No
Size of Dot.2.2507MOA
Adju. intensityNo
Parallax setting Parallax free
Working temperature range
Power Supply UnitNo
Battery lifespan.0h
Filled with Nitrogen
Lens coatings Fully Multicoated
Tube size/diameter No
FootprintAimpoint Micro standard
Mount type - IntegratedPicatinny
Mount length.0mm
Size of windowNo
Dot Sight TypeSmall tube sight
Water proof Yes
Fogproof Yes
Shock proofYes
Type of mount rail Yes


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Reviews & Testimonials

Reviews for Holosun Paralow HS403B

3 reviews
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403B By
Ottimo servizio della Optics-Trade, assistenza sulla spedizione da dieci e lode e molto veloci, GLS un poco meno.
Red dot veramente valido, con 6 colpi ho tarato a 60 metri, molto preciso e intuibile, ora non resta che provarlo su qualche cinghiale. Per ora 10+++ all'ottica e all' azienda.


Excellent service of the Optics-Trade, assistance on shipping by ten and very fast, GLS a little less.
Really good red dot, with 6 shots I calibrated to 60 meters, very precise and intuitive, now I just have to try it on some wild boar. For now 10 +++ optics and company.

(Posted on 05/01/2019)

Good budget red dot. By
Easy to use, good for the price.
No, its not a Aimpoint, but at this price it's a much cheaper option and from the reviews on youtube seems to stand up to some abuse.
Very happy, with the product and the service.

(Posted on 11/08/2017)

Great budget red dot By
I have to say I am really pleased with the quality of the Holosun HS403b. The glass is clear and the 2 MOA dot is quite good. It can be set bright enough to be visible in bright sunlight and it is small enough to allow precision shots.

Zeroing the red dot was quite easy, as it comes from the factory already centered and there is no need to chase it around and get it centered.

All in all, I am more than satisfied with this purchase.

(Posted on 06/01/2017)

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