Shield Sights SIS2: The Raw Truth Review

This review has been a long time coming. I first mentioned the Shield SIS2 when I wrote about my B&T GHM9 project and review back in May, 2024. I bought the Meprolight MPO-F months later, and still got that review out before this one. So what gives, Matt? Well, it had to do with limited opportunities to break the GHM9 back out to the range as well as some warranty work that I needed done on the SIS2 itself. But, we’ll get to that.

Earlier this year, I made a decision to explore what other electronic sight options were on the market besides Holosun. Call it a pinch of wanting to go against the grain of what everyone else was defaulting. Well, that and trying to find other options besides Chinese OEMs. When I started on my GHM9 project, the easy path would have been something like the Holosun AEMS that everyone was using. The Aimpoint Duty RDS was another option, as was the EOTech XPS2 that I had sitting on a shelf (and even used from time to time). But one manufacturer kept popping up for me as something I wanted to try- mainly because my friend Ilya (The Dark Lord of Optics) has spoken positively about them before.

Bottom Line Up Front

I purchased the Shield Switchable Interface Sight (SIS) 2 with my own funds back in April 2024 from my regular FFL, who also stocks a lot of optics and sights. I paid a retail price of $500.00 for the unit. It’s an enclosed miniature dot optic designed for the PCC/SMG market, but can also ride atop an optic like the Elcan or ACOG with an appropriate mounting plate.

The small 2 ounce aluminum sight feels robust. It’s also rated for water resistance for 30 minutes at 1 meter depth. Not SCUBA diving depth, but certainly no issues with rain or working around water.

The SIS has four reticle options, and they’re all really variations of either a 2 MOA dot, 8 MOA dot, and an optional 65 MOA ring around the dot. The automatic brightness mode is generally good to go, though I’ve certainly enjoyed having the option to switch to manual brightness during challenging illumination situations. Illumination itself is very bright, and I’ve had no issues in full daylight. I’ve not used them, but night vision modes are present.

The polycarbonate lens is clear, with no tint, though the slanted rear lens does sometimes pick up reflections of ceiling lights behind me at the range or in the house.

Early on I did have an issue with recoil causing the sight to turn off and reset. Shield was very fast with the RMA and warranty work, and when I got it back on the gun it’s had no issues since.

Overall, I’m quite happy with the sight, and I think it’s a worthy contender in the duty-grade enclosed mini dot space. You’ve got the Trijicon RCR which retails for a couple hundred more dollars. For roughly the same price as the SIS2, you’ve got the Aimpoint ACRO P-2 or Steiner MPS. Arguably, the SiS might be more durable than those as well, given several high level military units (particularly in the UK) switched to preferring the related Shield CQB instead of the Aimpoint. None of the competitiors have selectable reticles.

However, I think Shield needs to do a bit more to mature their footprint in the US with both brand power and information availability.

About Shield Sights

Shield is a British company formed in the early 1980’s by competitive shooter Jeremy White, later joined by James White. They’ve got history servicing the British Special Forces in a variety of capacities from range construction to weapons training and building suppressors for the UK Ministry of Defense.

Jeremy has a long history with IPSC and working with several well known companies like STI to work on their sales and marketing efforts. In 1996, Clive Paige approaches Jeremy to help design the first miniature red dot sight, US Patent US6327806. It was a wild departure from the larger Aimpoint optics that competitors were using at the time. Over the next several years, several companies start making variations of the Firepoint sight, including Doctor Optics, Tasco, and others.

In the early 2000s, Shield released the SMS. It also sees quick adoption by the UK Special Boat Service (SBS) as well as US Navy Seals and other SOF units who piggybacked them on the ACOG. Jeremy’s son James also joins the company and helps supply 2500 SMS units (branded as JPoints) to US SOCOM. A few years after that, Trijicon and Shield worked together to develop the RMR, which Shield provided the electronics for.

In 2010, Shield develops enclosed mini dots like the CQB sight that mounts atop the British fixed 4x ELCAN optic. Their products keep going through iterations, and in 2018 they release the RMSc for subcompact weapons. In 2023, they launched the CQS, which updated their classic rifle battle sight.

I’ll stop there, because we’re getting up to their current line of products.

The takeaway here is that Shield is the originator of the mini dot format that others have continued building on. Their primary customer is the UK Ministry of Defense and they have a pedigree of compact and tough optics just as much as well known US companies like Trijicon. Given their location in the UK, they’ve largely missed out on the US market, though.

Shield SIS2 Specs

The SIS2 has a relationship to the CQB/CQS line of optics. They share very similar design elements, with a few key differences that I’ll get to in a minute. I know you can read a spec sheet as well as I can, so here’s a quick summary just so you have an idea.

Out of the Box

The SIS2 comes in a small plastic box wrapped with a paper label. In the container is the sight, a cover, a CR2032 battery, stickers, three sets of mounting screws, and a stacking polymer mount for different heights. There’s a business card for additional information and a QR code that takes you to the user manual.

Oddly, if you actually follow the QR code and click on the SIS English user manual, you’re met with a 404 error. I let them know about this, but it still hasn’t been fixed as of this writing.

The SIS 2 is compact, and weighs 2.2 ounces. The body is 2.0″ long, 1.5″ wide, and 1.14″ tall. The front lens measured 0.85″ wide and 0.62″ tall, and it’s set back a bit from the metal housing. The rear lens measured 0.80″ wide and about 0.54″ tall. To give a comparison, the Steiner MPS (which I spent time with as well for another publication) weighs 2.05 ounces, has overall dimensions of 2.17″ long x 1.25″ wide x 1.38″ tall. The viewing window on the MPS measured 0.79″ wide and 0.63″ tall. The Aimpoint ACRO P-2 weighs 2.1 ounces, is 1.9″ long x 1.3″ wide x and 1.2″ tall. It also has a viewing window that’s 0.59″ wide x 0.59″ tall. So you can see that the Shield SIS 2 is slightly larger than the comparable enclosed mini dots in both overall dimensions as well as viewing space.

Compared to the first generation SIS model, the SIS2 removed the two lobed “humps” from the top of the optic and now sports a sleek flat housing. The anodized aluminum housing has two slanted “arms” reaching from the rear of the sight to the top. I suspect this both provides additional support should you drop it, but also helps prevent snagging on gear by not leaving any sharply angled surfaces to hook anything. Shield doesn’t specify what aluminum alloy they use, other than saying “aerospace grade,” but at least one review I found of the predecessor says it’s 6082. That’s still a tough aluminum that’s probably more than good enough, but it’s not 7075 like comparable options.

The right side of the housing has the large battery module for a CR2032. The left side has two sizable buttons for controlling illumination.

SIS2 Illumination

Shield likes to employ automatic brightness adjustment. The military-oriented CQB (and related CQS) sights are automatic brightness all of the time with no option to go manual. On those sights, the space on the left side of the optic houses a backup battery should the primary battery run out of power. Unlike those, the SIS2 allows you to utilize automatic brightness or manual brightness modes.

On automatic mode, the SIS2 has three settings (low-medium-high). Which switching to manual, there are 12 settings including night vision modes. Switching between manual and automatic is simple. Holding both buttons together for 1 second switches between them.

I found the automatic mode to be adequate for general use. Unlike the CQS (or the MPO-F I recently wrote up), the light sensor is not on the front of the housing for a “target facing” image. I’m guessing it’s on the inside of the enclosed space. That means it’s generally fine for detecting and adjusting to ambient light, but is challenged if you’re in a dark space and pointing at a bright object, as with using a weapon light.

When in automatic mode, the adjustments happen very quickly- like instant. I suppose it helps that there’s only a few automatic brightness levels, so I don’t really see it ticking up and down the levels.

On full brightness, it’s as bright as any other sight I have and great for bright daylight.

Battery life is reported to be about 1 year on average use, and there is no auto-shutoff or shake awake.

Reticle Design

The SIS2 has four reticle options. You can have a standalone 2 MOA dot, a standalone 8 MOA dot, or either of those with a 65 MOA ring around it. Unlike something like an EOTech, the 65 MOA ring is actually a ring of smaller dots. For a while I was using the 2 MOA dot with ring, but more prefer just the 8 MOA dot for the GHM9.

Switching between reticles is a matter of briefly pressing the “+” and “-” buttons simultaneously (not long enough to change the brightness modes). The reticle begins flashing and you cycle between options by pressing either “+” or “-” button. Press them together simultaneously again to accept the setting, or just leave it alone for five seconds and it will do it on its own.

The reticle is sharp enough for me, despite my astigmatism. The 8 MOA dot has a little bit more of a starburst to my eye, but not so much that it hurt my shooting. I still prefer having the brighter dot to draw my eye, and I don’t need that much precision on a gun like a GHM9 given my intended usage parameters.

To power off the sight, you press both buttons together and hold them down for a few seconds.

Mounting and Zeroing

The SIS2 uses a unique footprint to the SIS format. It’s a bit like a scaled up RMS footprint, with recoil lugs on the mounting surface and two screws that come from under the mount and into the optic’s body rather than screwing down from the top. Shield included one polymer 1913 mount in the box that’s an interesting design. There’s a base unit that clamps to the rail, and then a series of up to two stacking “ladders.” The number of ladders correlates to your preferred optic mounting height, with two ladders being a lower 1/3, one being absolute for AR-15 sights. You can mount the optic directly to the base as well for things like AKs or other platforms.

Once you’ve picked a height, you use the corresponding set of mounting screws that run up through the bottom of the base, through the ladders, and into the optic. Tightening them down sandwiches the whole thing together.

The system seems fine. Shield admits the included polymer mount is meant to be serviceable for duty use, but is really temporary until you choose another method. They also sell an aluminum version of the same ladder system as well as mounts for a variety of optics including ACOGs and Elcans. Alternatively, they have an adapter plate that allows the SIS to use any Aimpoint T-2 footprint mount. This is probably the route I’ll go in the future.

As for zeroing, it’s…different.

The SIS2 has the typical adjustments for elevation and windage that you’d expect, except for the fact that they do not have any sort of click to them. There are markings on the housing to indicate 2 MOA increments, but the screws themselves have no stop points as you rotate them. Shield says this is “infinitely adjustable” for accuracy so you can really narrow down and fine tune, but I’m not sold. Sure, it’s workable to get a zero and fine tune it, but not being about to count clicks is just…weird.

Furthermore, the lack of some kind of click retention makes me feel like there’s less there to keep the sight zeroed where I want it. I could be wrong, and Shield may have done a good job with this, I just find it…odd. That said, no issues with getting the sight zeroed.

Putting SIS2 to Work

With the preamble out of the way, let’s talk about how the sight performed for me.

The GHM9 is an interesting prospect because as-tested, it’s not the most stable platform. Without a stock or brace, I’m relying only on sling tension to stabilize the gun. This arrangement lends itself to something with a large viewing window like an EOTech- which I did use a lot early on. I bring that up to say that the smaller window of the SIS 2 still works very well for this arrangement. It’s just large enough to give me that sight picture I’m looking for without looking awkwardly large on such a small gun.

Up drills and the like were very easy. So the sight is doing its job well.

Optical Impressions

The clear polycarbonate lenses are nice. I’m so used to blue-tinted lenses on everything but my EOTech that it’s refreshing to see through a clear lens again. The rear lens slopes upward a bit. I’m not sure why they did this design choice, but it in certain lighting conditions it reflects a light source from above and behind me to enter my sight picture. It’s never prevented me from aiming, but it is distracting. There’s a notable blue-green tint to anything reflected back at my eye, even if I don’t detect the color looking through the lens itself. There’s definitely some kind of coatings on the lenses for antireflection.

Electronics Fault

There issue I ran into occurred on the second range trip out. About once every seven to ten shots, I noticed that the sight turned off. I’d press the buttons to turn it back on and it had reset the reticle and brightness back to factory defaults.

When I got home, I started trying to replicate the issue with dry fire. I was able to do it by roughly cycling the charging handle and letting the bolt fly home. I could reliably make the sight shut down every three or four attempts this way. There must have been something about that specific momentum impulse, because I could not replicate it any other way like smacking it from the sides or top (and not being gentle about it).

Warranty Experience

Not wanting to deal with a $500 sight that didn’t stand up to recoil, I contacted Shield through their site. I got a prompt response back from their HQ in the UK, and they agreed to issue an RMA and take a look. I got a paid shipping label and sent it off to them. In all, they had it for about two weeks and then it was back at my door. I tried asking what the issue was, but the email contact I had didn’t have a way of looking it up.The suspicion was that it was a faulty contact in the electronics.

After getting it back, I mounted it on the GHM9 once again and started replicating the dry fire. Working as hard as I could to be rough with the bolt, the sight stayed on and did not show any issues again.

Due to other obligations for articles, I didn’t get the GHM9 back out to the range again for some time. When I finally did, I ran another 150 rounds through it doing a variety of drills and tests, and there was no issue whatsoever. So it seems that the sight is working correctly, and I’m happy to say the whole experience was positive.

Final Thoughts: Should You Consider the SIS2?

The enclosed mini dot space is interesting because there are so few options that aren’t made in China. For the well known “duty grade” optics, you’ve got the Trijicon RCR, Aimpoint ACRO P-2, and Steiner MPS. The Trijicon costs significantly more than the others. The Aimpoint and Steiner are similarly priced to the SIS2, but come with tradeoffs in overall size and options of reticles.

On top of that, both the Aimpoint and Steiner were designed for pistol shooting rather than rifle or PCC, and Shield has other options that directly compete in the enclosed pistol dot market like the AMS and AMSc. Those two are similarly designed to the SIS2, but smaller and uses the common RMS/RMSc footprint.

On the still-not-made-in-China train, you’ve got something like the Meprolight MPO Pro-F, which is the enclosed version of the MPO-F I recently reviewed. It’s made in the Philippines, and the jury is still out on how “duty grade” it actually is.

All of that to say that I think Shield has carved an interesting niche for themselves here. At $500, it’s not inexpensive, and it’s clearly competing against the previously mentioned options from competitors that could just as easily mount to a PCC as they do a pistol. For PCC use, it’s also up against more traditional compact dot sights like the Aimpoint T2 or Duty RDS.

And that’s where I hit my conundrum. All said and done, I think my personal use case with the GHM9 is a better fit for the Aimpoint Duty RDS for the same cost. It has the legendary Aimpoint battery life, a common footprint with no need for adapters, and I’m perfectly fine with a standard red dot.

The Shield SIS2 is a fine optic, to be clear. I’m happy to keep it on my GHM9 for now, but I do see it eventually migrating to something else like a piggyback mount on my Elcan, or otherwise used as an offset dot for a precision gun.

If you need a very compact standalone sight that’s duty ready and designed for SMG/PCC/PDW or rifle use, then the SIS2 makes a ton of sense and I think offers a unique value proposition. Otherwise, I’d probably look elsewhere. Until then, I do hope Shield gains a stronger footprint in the US market, and I’m also looking forward to testing out their pistol-focused optics someday.