Sofirn SC21 Pro Flashlight Review

Sofirn SC21 Pro Flashlight Review

Sofirn updated the SC21 flashlight to a Pro version. The new one offers Anduril user interface and so you get great ramping features and more!

Official Specs and Features

Here’s a link to the Sofirn SC21 Pro flashlight product page.


Aside from this being the Pro version (and thus not the original SC21), there’s just one emitter option of the SC21 Pro. This body is available in multiple colors though.  There’s black (seen here), red, and green. Each of those is available as a package with or without cell, too. The cell (also seen in this review) adds $2, so obviously it’s a good addition.


On Sofirn’s website, it looks like the Sofirn SC21 Pro flashlight is $23.99 without cell and $25.99 with. The light is also available on for more, but I have a coupon that’ll last this whole month. Here’s an amazon referral link to the Sofirn SC21 Pro flashlight. The 20% coupon is this: 15IK9Q1E.

Short Review

If you’re an Andúril lover, this is a necessary upgrade. Anyway the price doesn’t seem to be much if any more than the original (depending on sale prices and whatnot) so there’s no good reason to avoid the Sofirn SC21 Pro flashlight if you’re in the market for a 16340 flashlight. Since Andúril 2 is out, I’d like to see A2 on this light. But this one is decidedly Andúril 1 – bear that in mind! (And despite what the manual you see below says….)

Long Review

The Big Table

Sofirn SC21 Pro flashlight
Emitter: Samsung LH351d (5000K)
Price in USD at publication time: $23.99
Cell: 1×16340
Turbo Runtime Graph High Runtime Graph
LVP? ?
Switch Type: E-Switch
Quiescent Current (mA): 0.18
On-Board Charging? Yes
Charge Port Type: USB-C
Charge Graph
Power off Charge Port with cell: all modes
without cell or body: “all modes” (just lower output)
Claimed Lumens (lm) 1000
Measured Lumens (at 30s) 887 (88.7% of claim)^
Candela per Lumen 7.6
Claimed Throw (m) 135
Candela (Calculated) in cd (at 30s) 202lux @ 5.432m = 5960cd
Throw (Calculated) (m) 154.4 (114.4% of claim)^
Claimed CCT 5000
Measured CCT Range (K) 4800-5200 Kelvin
Item provided for review by: Sofirn
All my Sofirn 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

Sofirn SC21 Pro Flashlight what's included

  • Sofirn SC21 Pro flashlight
  • Sofirn 800mAh 16340 (standard button top)
  • Spare o-rings (2)
  • Charge cable (USB to USB-C)
  • Lanyard
  • Pocket clip
  • Manual

Package and Manual

Sofirn SC21 Pro Flashlight box

Sofirn SC21 Pro Flashlight manual

Sofirn SC21 Pro Flashlight manual

Build Quality and Disassembly

Sofirn SC21 Pro Flashlight

There’s really not much if anything different about the SC21 Pro from the SC21. The build quality is still the same, for example.

There’s plenty to love in this tiny package. That “sort of aggressive” knurling provides ample grip for swapping the cells and just holding the light in general. The proud switch makes finding it for use very easy.

Here’s the tailcap, which has a little bump out to house the magnet.  The edge is also even with this bump out, and allows room for the lanyard holes.

Sofirn SC21 Pro Flashlight tailcap

The head comes off the body easily, over smooth anodized threads.  Because of this anodization, it’s possible to mechanically lock the light out with a very light loosening of the head.  I recommend this, as quiescent current is fairly high here.

Note in the photo below how accessible the flashing pads are. That’s a win for modders – it should be easy to flash in your current build of Andúril if you wish to do that. This is also a major update from the original SC21 – it did not (look to) have flashing pads like this.

Sofirn SC21 Pro Flashlight head off showing contacts

Only the tail ens sports a spring; the head has just a brass button.  I did not explore the option, but the spring looks to be removable, so you could remove the magnet if you wish.

Sofirn SC21 Pro Flashlight head off showing contacts

Size and Comps

Length: 73mm
Body Diameter: 22.5 mm
Weight: 39g (Not including pocket clip or battery)

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).

Sofirn SC21 Pro 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.

Sofirn SC21 Pro Flashlight beside the TorchLAB BOSS 35 (custom engraved)

Retention and Carry

A friction fit pocket clip is included, but not installed by default.

Sofirn SC21 Pro Flashlight with pocket clip off

This clip fits only on the tail end of the light but is a two-way clip.  I have historically not loved two-way clips and this is no exception, but the execution here is fairly good.  There’s a tradeoff being made though.  The clip is short, which means it doesn’t get in the way of head removal.  (This is good – the clip doesn’t scratch the head when twisting.)  But the clip is short, so while using this on a cap will work, the Sofirn SC21 flashlight will protrude by almost half of its body length over the front of the bill. Pick your poison?

Sofirn SC21 Pro Flashlight with pocket clip on

Also included on the Sofirn SC21 flashlight is a couple of lanyard hole attachment points.  These are interesting because they feature a gap to allow tailstanding while the lanyard is installed.

Sofirn SC21 Pro Flashlight lanyard installed

The idea here is great, but in reality, the implementation is less so – just give me two holes for the lanyard to go through, as a Convoy S2+ has, and let’s call it good.  Or maybe there’s some other explanation for this setup that I don’t yet know?

Power and Runtime

The Sofirn SC21 Pro flashlight is powered by a single lithium-ion cell – in this case, a 16340.  An appropriate cell is included – an 800mAh button top.

Sofirn SC21 Pro Flashlight with included 16340 cell Sofirn SC21 Pro Flashlight included 16340 cell

The cell is installed into the light in the usual way – positive end toward the head.

Sofirn SC21 Pro Flashlight included 16340 cell installed

Runtimes follow.  Turbo drifts down fairly quickly, but not in such a way that it seems to be gaming the ANSI standard. For all of these runtime tests I did calibrate Andúril thermal settings before testing.

Sofirn SC21 Pro Flashlight runtime graph

Sofirn SC21 Pro Flashlight runtime graph Sofirn SC21 Pro Flashlight runtime graph

You might like to see my original SC21 review. On those tests, the highest output looks similar to the one above, but the two second highest outputs are basically flat. That could be a reasonable deciding factor between these two lights. Between having Andúril and having flat output, I might personally pick a flat output.


On-board charging is available and happens via this USB-C port in the head.  A press-in cover protects the charge port.

Sofirn includes a quite nice USB to USB-C cable.

Sofirn SC21 Pro flashlight charging cable

I tested the charge cycle with both USB to USB-C and C to C.  The charge looks about the same for either, but it’s good to know that C to C works just fine.

Sofirn SC21 Pro flashlight charging graph Sofirn SC21 Pro flashlight charging graph

Modes and Currents

Mode Mode Claimed Output (lm) Claimed Runtime Measured Lumens Tailcap Amps
Double Click Turbo initial: 1023
30s: 887
Highest Stepped 542 2.24
351 1.26
246 0.64
141 0.40
71 0.19
25.4 0.06
Lowest Stepped 4.1 low
Lowest Ramping 0.20 low

Pulse Width Modulation

There is PWM on all modes except Turbo (and maybe even on Turbo, but on Turbo it’s acceptable).

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

The Sofirn SC21 Pro flashlight is controlled by a single switch.  It’s an e-switch on the side of the head. Note that the manual says this light has Andúril 2, but my copy definitely has Andúril 1. An easy way to check if a light is Andúril 1 or Andúril 2 is perform 6C (six clicks) from off. If the light goes into Muggle mode (or “responds in basically any way”) then it’s Andúril 1.  The action “6C” does not have a result in Andúril 2.

Sofirn SC21 Pro Flashlight e-switch Sofirn SC21 Pro Flashlight e-switch profile

There’s a surprising amount of travel on this switch.  It’s also quite proud.

This switch also has indicating features – below it’s seen indicating red for low voltage.  Notably, the switch will indicate for 5 seconds after the light is turned on, as follows:

Green: remaining battery power is good
Red: remaining battery power is poor (less than 30%)
Red Flashing: recharge or swap cell immediately.

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 sort of generica user interface table for Andúril 1 anyway! Every feature mentioned here might not apply to the Sofirn SC21 Pro flashlight.

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)
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.

LED and Beam

One of the main important features of the Sofirn SC21 flashlight is that it features a Samsung LH351d emitter.  This is a 5000K temperature, and I applaud the great choice here by Sofirn. This is not an update from the original SC21.

Sofirn SC21 Pro Flashlight emitter

Sofirn didn’t go for “short” on the SC21 Pro and used a nice deep reflector.  This gives a great beam profile.

Sofirn SC21 Pro Flashlight emitter on

Also, see here that the switch is indicating in green.

Sofirn SC21 Pro Flashlight emitter on Sofirn SC21 Pro Flashlight emitter on

LED Color Report (CRI and CCT)

The readings on this SC21 show a CCT of 4800K to around 5200K and CRI around 90.  Both of these are good.


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 about the Sofirn SC21 Flashlight

  • Good to see another 16340 flashlight available!
  • User interface offers something for most users (ie ramping is there if you want it)
  • Switch is proud and easy to find
  • Indicator on switch is very clear and clean
  • Complete package is a very good and low cost
  • USB-C charging (and also C to C charging works!)
  • Good choice of 5000K emitter
  • Nice beam profile
  • Andúril user interface
  • Looks like flashing pads are very accessible

What I don’t like about the Sofirn SC21 Flashlight

  • Two-way pocket clip
  • Not Andúril 2. Lights by this point should be shipping with Andúril 2


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