Noctigon K1 21700 Flashlight Review

Noctigon K1 21700 Flashlight Review

The Noctigon K1 21700 Flashlight is a feature-rich flashlight with many emitter options – seen here with an Osram KW CSLNM1.TG.  Read on for a bit of testing.

Official Specs and Features of the Noctigon K1 21700 Flashlight

Here’s a link to the Noctigon K1 21700 flashlight product page.


Three body colors are available.  Black, Dark Grey, and green (seen here).  All of these bodies offer the same feature set.

You’ll note probably, that the emitter being seen in this review is not in that list above!  That’s because this one is a special order… and you could order it too if you wanted.  You’d need to send an email to work out those details, but it can be done (and it’s easy!)


As seen here, the Noctigon K1 21700 Flashlight goes for $89.95.

Short Review

Let me meme this short review right quick:

You probably remember that post from Reddit.  This is a review of that flashlight.  It’s a very, very good thrower.  It’s the beacon.

Long Review

The Big Table

Noctigon K1 21700 Flashlight
Emitter: Osram KW CSLNM1.TG ((1mm2))
Price in USD at publication time: $89.95
Cell: 1×21700
Turbo Runtime Graph Turbo Runtime Graph
Switch Type: E-Switch
Quiescent Current (mA): ?
On-Board Charging? Yes
Charge Port Type: USB-C
Charge Graph
Power off Charge Port
Claimed Lumens (lm) 900
Measured Lumens (at 30s) 790 (87.8% of claim)^
Candela per Lumen 739.7
Claimed Throw (m) 1612.5
Candela (Calculated) in cd (at 30s) 11940lux @ 7.18m = 615536cd
Throw (Calculated) (m) 1569.1 (97.3% of claim)^
All my Noctigon reviews!

^ Measurement disclaimer:  I am an amateur flashlight reviewer.  I don’t have $10,000 or even $1,000 worth of testing equipment.  I test output and such in PVC tubes!!  Please consider claims within 10% of what I measure to be perfectly reasonable (accurate, even).

What’s Included

Noctigon K1 21700 Flashlight what's included

Mine’s a loaner without the full retail package.  I got the Noctigon K1 21700 Flashlight and a carry holster only.

Package and Manual

Noctigon uses a cardboard box with a label sticker, so that’s what you’re likely to get with this one, too.

There is no manual (!!).  Maybe there was and it wasn’t included with my package.  But this is a typical Anduril flashlight, so you probably already know how that works.  I’ll cover it below anyway.

Build Quality and Disassembly

Noctigon K1 21700 Flashlight

The same that I said about the Noctigon K9.3 can be said about the Noctigon K1 21700 flashlight.  It’s hard to opine enough about the build quality of this light.  Used to be that these were a low-cost category of lights.  With this light clocking in at around $90, that can no longer be said.  And we don’t have to hold it to a “higher standard” but the build quality needs to be commensurate with the price asked.

It is – this light is extremely well built, and I have no complaints.  In fact, this one comes to me used (or “as a user” so to speak) and it’s still nearly flawless.  That speaks to the owner having soft touch, or the light being very robust and taking use very well (or both, obviously).  There are some sharp edges that have worn down a bit from use, but even that is fairly minimal.

Noctigon uses minimal branding on the K1 21700 Flashlight.  It’s seen only on the tailcap.

Noctigon K1 21700 Flashlight branding

As with other Noctigon lights, the tailcap has reeding which aids in tailcap removal.

Noctigon K1 21700 Flashlight reeding on tailcap

On the body is deep and very consistent knurling.

Noctigon K1 21700 Flashlight knurling

Cooling fins on the head are deep and well finished.  Smartly, the bezel is stainless steel.

Noctigon K1 21700 Flashlight head cooling fins

The Noctigon K1 21700 flashlight also benefits from some cooling fins in the “neck” area, around the switch.

Noctigon K1 21700 Flashlight cooling

Removing the tailcap reveals anodized square-cut threads, with minimal lube.  They’re quite long threads, so many twists are required.  The tailcap has a spring, too.

Noctigon K1 21700 Flashlight tailcap threads

It’s also possible to remove the head, and the same thread conditions apply here.  The cell tube is not reversible.

Noctigon K1 21700 Flashlight head threads

Both head and tail have springs.

Noctigon K1 21700 Flashlight contact points

The driver, seen below, looks to have flashing pads, which should allow flashing new firmware into the light.

Noctigon K1 21700 Flashlight head spring

The cell tube is completely removable.  There are no other size cell tubes available, though.

Noctigon K1 21700 Flashlight cell tube

Size and Comps

Dimensions: 173mm (length) * 72mm (head) * 26.5mm (body)

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).

Noctigon K1 21700 Flashlight in hand

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.

Noctigon K1 21700 Flashlight beside torchlab boss 35 Noctigon K1 21700 Flashlight beside torchlab boss 35

Hey shawty, it’s your birthday.

Noctigon K1 21700 Flashlight shawty

Retention and Carry

The main way to carry this Noctigon K1 21700 flashlight is going to be the included pouch.

Noctigon K1 21700 Flashlight carry holster

It’s a directional pouch, with bezel-up carry only.

Noctigon K1 21700 Flashlight carry holster

The light hangs out the bottom of the holster, and the light can not be used while in place.

Noctigon K1 21700 Flashlight carry holster

There is a lanyard too, which attaches through this hole in the tailcap.

Power and Runtime

The Noctigon K1 21700 flashlight runs on one lithium-ion.  The default is a single 21700.  I tested with a flat top unprotected cell – the Vapcell seen below.

Noctigon K1 21700 Flashlight with 21700 cell

The cell is installed into the light in the usual way – positive terminal toward the head.  Through the tailcap end (as seen below) is the only way to install cells, too.  You will see why below.

Noctigon K1 21700 Flashlight with 21700 cell installed

Below are a couple of runtimes.  Turbo only, but both before and after calibration.

Noctigon K1 21700 flashlight runtime graph Noctigon K1 21700 flashlight runtime graph


Surprisingly the Noctigon K1 21700 flashlight has built-in charging! There’s a USB-C port on the positive side of the cell tube.

Noctigon K1 21700 Flashlight charge port

This is why the cell can only go into the light through the tail end – the head end is “captured.”  Note the difference in this one and the K9.3 – this one lacks the opaque plastic guard.  I’m not sure if the owner removed it, or if it shipped this way.

Noctigon K1 21700 Flashlight charge port

Anyway, I like the view into those electronics.  And it really makes the red or green charge indicators pop!!  Red means “charging” and green means “charging completed.”

Noctigon K1 21700 Flashlight charge port

A charge cable isn’t included but I can say that either USB or USB-C sources work just fine with this setup.  Charging is about the same between the two, and fairly quick.

Noctigon K1 21700 flashlight charge graph

Modes and Currents

Mode Mode Claimed Output (lm) Claimed Runtime Measured Lumens Tailcap Amps
Turbo (double click from on state) 900 790 4.68
7 687 3.24
6 527 2.13
5 371 1.32
4 226 0.74
3 119 0.36
2 52 0.14
1 12 0.03
Lowest (Accessible from the ramping group only) 3 0.01

Pulse Width Modulation

For reference, here’s a baseline shot, with all the room lights off and almost nothing hitting the sensor.  Also, here’s the light with the worst PWM I could find.  I’m adding multiple timescales, so it’ll be easier to compare to the test light.  Unfortunately, the PWM on this light is so bad that it doesn’t even work with my normal scale, with is 50 microseconds (50us).  10ms5ms2ms1ms0.5ms0.2ms.  In a display faster than 0.2ms or so, the on/off cycle is more than one screen, so it’d just (very incorrectly) look like a flat line.  I wrote more about this Ultrafire WF-602C flashlight and explained a little about PWM too.

User Interface and Operation

A side e-switch is used in the Noctigon K1 21700 flashlight.  This switch (unlike on the K9.3) is multi-colored and offers some information about cell voltage and the like.

Noctigon K1 21700 Flashlight indicating e-switch

The switch is proud, but the action is low.

Noctigon K1 21700 Flashlight indicating e-switch

Noctigon K1 21700 Flashlight indicating e-switch Noctigon K1 21700 Flashlight indicating e-switch

The UI here is ToyKeeper’s Anduril, which at this point is very well covered.  I’ve reviewed other lights with it, too.  Here’s ToyKeeper’s UI graphic:

Here’s a UI table anyway!

State Action Result
Off Hold On (Low)
Off Click On (Mode Memory)
Off Click 2x Highest Hybrid Mode
Off Click 3x Blinkie Mode Group
Off Click 4x Lockout
Off Click 5x Momentary
Off Click 6x Muggle
Off Click, Click, Hold Strobe Group (Mode Memory Strobe)
On Click, Click, Hold Switch between Channels (Main Channel and Secondary Channel)
Strobe Group Click 2x Strobe Cycle (Candle > Bike Flasher > Party Strobe > Tactical Strobe > Lightning Storm)
Blinkie Mode Group Click 2x Blinke Cycle (Sunset > Beacon > TempCheck > BattCheck)
On Click 3x Switch between Stepped and Smooth Ramp
On Click 4x Ramp Configuration
TempCheck Click 4x Thermal Configuration
Beacon Click 4x Beacon Configuration
Lockout Click 4x Off
Strobe Group Click Off
(Basically) On Click Off
Candle Click 3x 30-minute timer to off
Strobe Group Hold Heighten selected mode (Make faster or brighter)
Strobe Group Click, Hold Lessen selected mode (Make slower or dimmer)
On Click 2x FET Turbo
Ramp Configuration [Wait for Single flash] Click N time for level N. Selection of the “Low” you like best by clicking 1, 2, 3, etc. where 1, 2, 3, etc are different levels of low.
Ramp Configuration [Wait for Second flash] Click N time for 1+Turbo-N. Selection of the “Ceiling” you like best by clicking 1, 2, 3, etc. where 1, 2, 3, etc are different Ceiling levels.
Ramp Configuration [Wait for Third flash] Click for how many steps you want in Stepped mode. Sets Number of Steps.
Thermal Configuration [Wait for First flash] Click for N times for N degrees C. Displays Current Temperature.
Thermal Configuration [Wait for Second flash] Click for N times for 30C + N. Sets Temperature Limit.
Beacon Configuration [Wait for First flash] Click for N times N seconds per flash Sets Beacon Speed.

If you want to see how to calibrate the thermals, see this part of the FW1A review.

I checked this as Version 20191217 of Anduril.

LED and Beam

By special request to this user got an Osram Flat White Osram KW CSLNM1.TG (1mm2) emitter in the K1.

Noctigon K1 21700 Flashlight emitter

That’s an option you might or might not like – it might be a little cooler than you wanted (see below), but it will provide the best throw out of those options listed.

Noctigon K1 21700 Flashlight reflector

As a single emitter flashlight, this light gets fitted with a smooth deep reflector.  Perfect for throw!

Noctigon K1 21700 Flashlight reflector

And wow does it throw.

LED Color Report (CRI and CCT)

As the current to the emitter goes up, the CCT goes up (dramatically) too.  I was unable to test the higher modes because the extreme throwyness of this light saturates my tester.


These beamshots are always with the following settings:  f8, ISO100, 0.3s shutter, and manual 5000K exposure.

Tint vs BLF-348 ( 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 219b BLF-348 because it’s inexpensive and has the best tint!


What I like

  • Great build quality
  • The beacons are lit
  • Plenty of emitter options
  • USB-C charging works well (and quickly)
  • Andúril user interface
  • I love that a 4000K XHP35 HI is available.  Such a great emitter if you prioritize CCT over just extreme throw.

What I don’t like

  • No belt clip


  • This light was provided by barry_baltimore for review. I was not paid to write this review.
  • This content originally appeared at  Please visit there for the best experience!
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