Klarus XT21C Tactical Flashlight Review
Klarus has released the XT21C, a tactical flashlight featuring an included 21700 cell, dual switch interface, and great throw! Read on!
Official Specs and Features
Here’s a link to the Klarus XT21C tactical flashlight product page.
Versions
There is only one version of the XT21C.
Price
Klarus sells the XT21C tactical flashlight for $104.95. This price includes the 21700 cell, too.
Short Review
Tactical flashlights aren’t foreign to Klarus. This one is well refined and I’d say meets the needs of a tactical flashlight user. The mode order from highest to lowest, while maybe not suited to EDC roles, is great as a tactical light. Output is very high. Throw is very long. All in all, this is a solid offering.
Long Review
The Big Table
Klarus XT21C Tactical Flashlight | |
---|---|
Emitter: | Luminus SST-70 |
Price in USD at publication time: | $104.95 |
Cell: | 1×21700 |
High Runtime Graph | Medium Runtime Graph |
LVP? | Yes |
Switch Type: | Both |
Quiescent Current (mA): | ? |
On-Board Charging? | Yes |
Charge Port Type: | USB-C |
Charge Graph | |
Power off Charge Port | |
Claimed Lumens (lm) | 3200 |
Measured Lumens (at 30s) | 2544 (79.5% of claim)^ |
Candela per Lumen | 14.4 |
Claimed Throw (m) | 324 |
Candela (Calculated) in cd (at 30s) | 1135lux @ 4.705m = 25126cd |
Throw (Calculated) (m) | 317.0 (97.8% of claim)^ |
Claimed CCT | – |
Measured CCT Range (K) | 5600-6100 Kelvin |
Item provided for review by: | Klarus |
All my Klarus reviews! |
^ Measurement disclaimer: Testing flashlights is my hobby. I use hobbyist-level equipment for testing, including some I made myself. Try not to get buried in the details of manufacturer specifications versus measurements recorded here; A certain amount of difference (say, 10 or 15%) is perfectly reasonable.
What’s Included
- Klarus XT21C tactical flashlight
- Nylon holster
- Klarus 5000mAh 21700 (customized)
- Charging cable (USB to USB-C)
- Lanyard
- Spare o-ring
- Manual
Package and Manual
Build Quality and Disassembly
I said above that there’s just one version of the XT21C. That’s true. However, there are also very similar lights by Klarus. I’ve tested a couple. The Klarus XT2CR Pro is very similar. The Klarus XT11GT Pro is even more similar.
In fact, aside from the different emitter and cell size, I’d say the XT21C is an update to the XT11GT Pro. Nothing wrong with that – the XT11GT Pro was a good light.
The threads on the tailcap are square-cut and anodized, and not too long. The walls feel a bit thinner in this section, but I think it’s just this section – farther down the barrel I believe they are thicker.
There are springs on the head and tail, as there should be on a tactical light. The extra on the tailcap has to do with the dual switches.
Size and Comps
35mm x 25.4mm x 146.5mm
Weight: 109.8g without cell.
If the flashlight will headstand, I’ll show it here (usually the third photo). If the flashlight will tailstand, I’ll show that here, too (usually the fourth photo).
Here’s the test light with the venerable Convoy S2+. Mine’s a custom “baked” edition Nichia 219b triple. A very nice 18650 light.
And here’s the light beside my custom engraved TorchLAB BOSS 35, an 18350 light. I reviewed the aluminum version of that light in both 35 and 70 formats.
Retention and Carry
There’s a pocket clip included and attached. It’s a friction fit clip and lives on the tail end only. For belt carry it’s sufficient.
The included lanyard could attach to the clip in the holes seen above, or in this hole on the tailcap. The tailcap will be much more secure.
A nylon pouch is included. The carry is bezel-up only, and there aren’t any holes for in-holster use.
Power and Runtime
The Klarus XT21C tactical flashlight runs on a single lithium-ion cell. The required type cell is included at the purchase price, too. This is a 5000mAh 21700 cell.
The cell isn’t quite standard, though. It has this positive/negative terminal on one end. This is required for operation of the XT21C, unfortunately.
Here you can better see the protective shroud around the positive connection. This will prevent charging the 21700 in a bay-style charger.
The cell fits into the light in the usual way – positive terminal toward the head.
Here are a couple of runtime graphs.
I observe (and the manual states) the light only switches down to a very low output when the cell voltage is low. The output is very low – not usable tactically, but certainly enough to find another cell or whatever.
There’s an indicator in the head of the flashlight, too. This indicator will light up for 5 seconds after the light is turned on. It indicates as follows:
Green: 70-100% capacity remaining
Orange: 30-70% capacity remaining
Red: <30% capacity remaining
Red flashing: <10% capacity remaining
Charging
The Klarus XT21C tactical flashlight has built-in charging. The charge port is USB-C and has a snug press-in cover.
A USB to USB-C cable is included.
Here’s one charge test. Fairly standard fare here, with the charge essentially ending around 190 minutes.
During charging, the indicator in the head is red. When the indicator is green, charging is completed. If the indicator is yellow, something is wrong.
Modes and Currents
Mode | Mode Claimed Output (lm) | Claimed Runtime | Measured Lumens | Tailcap Amps |
---|---|---|---|---|
High | 3200/800 | 3m/4h | 2544 | – |
Medium | 400 | 7h | 448 | – |
Low | 100 | 20h | 112 | – |
Moon | 5 | 240h | 4.3 | – |
Pulse Width Modulation
Here, as below, the mode order is represented: the graphs from left to right are in descending brightness.
Here you can see a “baseline” – a chart with almost no light hitting the sensor.
Then there’s the Ultrafire WF-602C flashlight, which has some of the worst PWM I’ve seen. It’s so bad that I used a post about it to explain PWM! Here are multiple timescales (10ms, 5ms, 2ms, 1ms, 0.5ms, 0.2ms) to make comparing this “worst” PWM light to the test light easier. That post also explains why I didn’t test the WF-602C at the usual 50us scale.
User Interface and Operation
There are two switches on the Klarus XT21C tactical flashlight. As this is a tactical-use light, the switches are both on the tailcap.
One’s a paddle switch, and one is a mechanical clicky. It’s a fairly standard tactical setup.
There are technically two mode groups. As shipped (and tested here), the light is in the “Tactical Setting.” Also available is the “Outdoor Setting.” The manual states that the default is Tactical. The other is Outdoor. Mine actually shipped in Outdoor. Switch between the two as follows:
From off, hold the paddle switch (“Mode”) until the indicator switch goes from green to red/green flashing. Then tap the Primary switch. You can release or leave the light on; the group is changed.
This user interface is just like the Klarus XT11GT Pro, which I reviewed.
Here’s a UI table for Tactical mode.
State | Action | Result |
---|---|---|
Off | Click Primary Switch | High |
Off | Tap Primary Switch | Momentary High |
Off | Hold Paddle Switch (Mode Switch) | Strobe |
Off | Tap Mode Switch | Momentary Strobe |
On | Click Mode Switch | Mode advance (HML Moon) |
On | Click Primary Switch | Off |
Here’s a UI table for Outdoor mode.
State | Action | Result |
---|---|---|
Any | Click Primary Switch | High |
Any | Tap Primary Switch | Momentary High |
Off | Tap Paddle Switch (Mode Switch) | Momentary Moon |
Off | Hold Paddle Switch (Mode Switch) (~1s) | Moon |
On from Mode Switch | Click Mode Switch | Mode advance (High Moon Low Medium) |
On from Primary Switch | Click Mode Switch | Mode advance (High Moon Low Medium) |
On | Click Primary Switch | Off |
On | Hold Mode Switch | SOS |
LED and Beam
The emitter of choice for this light is a Luminus SST-70. The emitter benefits from a lightly orange peeled and deep reflector. Klarus doesn’t state the CCT of this emitter as far as I can see, but it wouldn’t be a surprise for it to be cool white.
The bezel does unscrew readily.
The bezel is somewhat aggressive, and as such allows light to shine out when headstanding.
LED Color Report (CRI and CCT)
Even on the highest setting, we’re only seeing around 6200K, which isn’t really all that terrible, particularly given that this is a tactical light. On the lower modes, we’re seeing well under 6000K. That’s great! The CRI is not high, but also not a surprise for it to be around 70.
Beamshots
These beamshots are always with the following settings: f8, ISO100, 0.3s shutter, and manual 5000K exposure. These photos are taken at floor level and the beam hits the ceiling around 9 feet away.
Tint vs BLF-348 (KillzoneFlashlights.com 219b version) (affiliate link)
I keep the test flashlight on the left, and the BLF-348 reference flashlight on the right.
I compare everything to the KillzoneFlashlights.com 219b BLF-348 because it’s inexpensive and has the best tint!
Conclusion
What I like
- Complete package
- USB-C Charging
- Interface which allows choice (specifically the Turbo to Low direction option in the Outdoor group, which is unusual)
- No PWM
- Lower modes are under 6000K, which is perfectly great.
- Really nice build quality (and feels important in hand)
- Updated user interface with good moonlight access in the Outdoor Setting
What I don’t like
- USB-C charging could be considered slow at 1.1A. The cell could handle much more, and USB-C could too.
- Cool white emitter
- Customized 21700 cell. Despite this becoming standard, I don’t like it. (However, with the charging setup, I do sort of get it, and the cell is included.)
- Price – at $105, this isn’t an inexpensive light.
Notes
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