Introduction
I’ve come to love Streamlight products for their consistency and quality at an affordable price. A couple months ago, they announced their Protac Rail Mount HL-X PRO USB, which boasts 50,000 candela and 1,000 lumens.
If it meets its specs, this light will keep Streamlight relevant in a sea of high-candela competition from Modlite and SureFire.
First Impressions
The Streamlight comes with everything you need to get started, whether you’re running M-Lok or pic rail. This saves you a fair amount of money if you don’t already have this equipment, at an overall price that’s still cheaper than the competition (who often don’t include all this hardware).
It’s a bit tricky to find this light for sale as a quick Google search will yield results for the previous generation. Here’s the product page on Amazon.
Manufacturer Claims and Specs
Here are a few quick specs for the Streamlight.
| Specification | Streamlight Protac Rail Mount HL-X Pro USB |
| Head Diameter | 36.7 mm (1.44 inches) |
| Overall Length | ~142mm (~5.6 inches) |
| Waterproofing (with remote pressure switch) | IP54 (water resistant) |
| Waterproofing (without remote pressure switch) | IP67 (waterproof to one meter for 30 minutes) |
| Battery Type | Streamlight SL-B26 or 2x CR123A |
| Lumens | 1,000 |
| Candela | 50,000 |
| Runtime | 1.75 Hours |
| Price (MSRP) | $266.00 (street price ~$140 depending upon configuration) |
Let’s compare Streamlight’s claims against our real-world measurements.
Into the Lab: Lumens, Candela, Color Temperature and CRI
For these tests, I used the battery that came with the light. I did not test with CR123 batteries.
Lumens
Streamlight claims 1,000 lumens for this light. We loaded it with a freshly-charged battery and let it run in our integrating sphere to test this claim. Here are the results:
Let’s get a closer look at those first ten minutes:
Nice! It produces over 600 lumens for an hour and fifty minutes, which should be ample time to resolve a situation which requires a rifle-mounted light.
ANSI-Plato spec for lumens is to sample output between thirty seconds and two minutes. By this measure, the Streamlight produces 1,084 lumens, which exceeds its claim.
This is the sort of consistency we’ve come to expect from Streamlight.
Candela
The Streamlight claims 50,000 candela.
ANSI-Plato spec is to test candela at thirty seconds, but since lights are usually brightest at zero seconds, it’s helpful to measure that as well.
| Candela (zero seconds) | Candela (thirty seconds) |
| 51760 | 50450 |
By these measurements, Streamlight is right on with their specs.
The Streamlight’s 50,000 candela candela may not seem like much when there are other lights producing 100,000, but it’s still blinding at close to medium range and throws light respectable distances. The Streamlight also has a fairly large hotspot, unlike the tight and narrow beam that you get when you have 100,000 candela. A larger hotspot preserves more of your peripheral vision, which is particularly helpful indoors.
Color Temperature and CRI
While light quality is not generally the focus of tactical lights, it’s still useful information to measure, as it helps us understand what to expect when observing objects illuminated by a given light.
The Streamlight is solid in other respects, but it’s not so great here.
70 CRI and 7083 Kelvin is unfortunately the norm for tactical lights, but it’s a pretty low bar. If you get this light, expect cold, washed-out colors when illuminating targets.
That said, high-quality light almost always comes at the cost of lumen output. Given that the Streamlight is a budget-friendly high-output light, these results are expected.
Final Thoughts
The Streamlight Protac Rail Mount HL-X Pro USB delivers respectable output at a reasonable price. Personally, I think it strikes a nice balance between lumens and candela, and the poor light quality isn’t a huge issue for me. This light will probably end up on one of my rifles.
Here is a quick list of pros and cons:
| Pro | Con |
| Respectable output Excellent runtime Dual-fuel capability Competitive price Included hardware | Made in China Poor CRI and color temperature |
