The Thrunite BSS V4 Desert Tan is a light I’ve had for a while, and have been figuring out how to review.  My review copy doesn’t work right…. read on for more info on why!

Official Specs and Features

Here’s a link to the Thrunite BSS V4 Desert Tan Flashlight product page.


There are at least two versions of the Thrunite BSS V4 – black, and this Desert Tan version.  And there’s also the Wowtac version, which I have reviewed recently, too.


The Thrunite BSS V4 Desert Tan sells for $65.95, and is available now.  The black version is a little less expensive, at around $60.

Short Review

All in all, this is really not all that different from the Wowtac BSS V4 which I already reviewed.  The emitter is different, of course, but the Thrunite BSS V4 Desert Tan seems to be cool white only (whereas the Wowtac version was available in neutral white.)  Everything about the light is good for its purpose, except that my review copy doesn’t work right.  You can see more about why below.

But the Light Doesn’t Work

But let’s address the light not working right, and why I’d review it here.  And also why I’ll probably not be too hard on the light not working right….

First of all, if you got this light from Thrunite, working the way it does, Thrunite would support you.  Probably what they’d do is just send a completely new light.  Thrunite isn’t some company you can’t get in touch with in multiple ways, like one of my other non-working flashlights.  Furthermore, this is a binary fault – either it’s out-of-the-box not working right, or it’s fine.  This isn’t a problem that will crop up down the road.

Why didn’t they just send a replacement for this review then?  Well they already sent the one light as a review sample (read: free), and review samples do not grow on trees.  It’s too costly for them to have the light sent back for to them for repair or discovery, and it’s also more costly than desirable to send me another review light.

Thirdly, there are no other reports of this, so my copy does just seem like bad dumb luck.  I got a lemon, and that happens.

Why would I review a non-working light, then?  Well, I accepted the light as a review sample, and to be honest if I don’t review it, I feel like I haven’t done my end of the bargain.  Reviewing it allows me to move it to the proper column in my spreadsheet.  And it’s data for you, too.  Honestly a review like this is even more work than a “regular” review, because I have to explain so many unusual things….

Long Review

The Big Table

I didn’t take any measurements, because I can’t trust that they’ll be accurate.  So no table.

  • 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

what's included

  • Thrunite BSS V4 Desert Tan Flashlight
  • Wowtac 3100mAh 18650
  • Pocket clip
  • Nylon pouch
  • Replacement switch cover
  • Replacement charge port cover (2)
  • Spare o-rings (2)
  • Lanyard
  • Red lens to replace crenelated bezel
  • Manual etc

Thrunite BSS V4 Desert Tan Package and Manual

box box


Build Quality and Disassembly

feature photo

The bezel is striking.  It’s easy to remove, and the light works fine without it.

Here’s the top-down view.

top down views

Black Scout Survival logo is on the head – it feels laser etched instead of silk screened or anything like that.

top down views top down views top down views top down views

This design on the tailcap does little to help with unscrewing the tailcap for cell swaps.

top down views

This strike bezel unscrews very easily (but not accidentally).

strike bezel removed

The light isn’t designed to be used without a bezel, but the lens didn’t fall out.

strike bezel removed

This is why the bezel is so removable:  There’s a red screw-in filter.  The filter precludes use of the strike bezel.

color bezel installed reflection

Unlike the strike bezel, the red filter is flush on the front.


The threads on the tail are square cut, fairly short, and unanodized.

tailcap off

There’s an inner tube on the cell tube.

cell tube

The head end has a brass button.  The tailcap has a big thick double spring.

spring and button

Size and Comps

Dimension: 146.5mm x 28mm x 25.4mm
Weight: 98g (NOT included the battery weight)

If a light will headstand, I’ll show it here (usually the third photo).  If a light 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 format.

beside torchlab boss 35

Retention and Carry

A nylon pouch is included.  The light will fit in either orientation, but there are no holes in either end.  So the light must be remove for use.

in nylon pouch

The light will go into the pouch in either orientation.

in nylon pouch

Also included is a friction fit pocket clip, which goes only one direction, and only on the tail end of the light.  So bezel down carry only.

Clip hug!

pocket clip hug

The included lanyard fits in the tailcap loop.

lanyard installed

Power and Runtime

The Thrunite BSS v4 runs on a single 18650 liion cell.  A proper cell is included – 3100mAh button top.  However even the shortest flat top unprotected cell seems to work just fine in the light.

included 18650

Note that this is a Wowtac branded cell.  Thrunite and Wowtac are effectively the same company, so this is no real surprise here.

The cell is installed in the usual way – positive terminal toward head.

included 18650 installed

Now, I didn’t test any running of this light.  You can see later why specifically – when on turbo, the light gets angry blue.  So something happens to be wrong with my review sample.

Even the lower modes don’t look right, because they seem out of order.  So I don’t trust any output of my review copy, and didn’t test any of it.


The BSS v4 has on-board charging too, in the form of a micro-USB port in the head.  This port is opposite the e-switch.

An appropriate cable is included:  USB to micro-USB.

Same story with charging as the other stuff – I didn’t test charging.

Modes and Currents

Not tested!

Mode Mode Claimed Output (lm) Claimed Runtime Measured Lumens Tailcap Amps
Turbo 2523-614 125s-147m
High 1426-634 130s-150m
Medium 350 4.5h
Low 33 55h42m
Firefly 0.54 56d

Pulse Width Modulation

Not tested, though we know from the Wowtac version that there is no pwm on any mode.

For reference, here’s a baseline shot, with all the room lights off and almost nothing hitting the sensor.  And here’s the worst PWM light I have ever owned.  Also one of the very first lights I ordered directly from China!

User Interface and Operation

There are two switches on the BSS v4.  First is the mechanical tail switch.

clicky switch

Next is the indicating e-switch on the head.  Note that this one has a metal cover.  (Metal, or plastic, either way it’s not rubber and soft.)

indicating e-switch indicating e-switch profile

Here’s a UI table!

State Action Result
Any (Unlocked) Click Tail Switch Turbo
Any (Unlocked) Tap Tail Switch Momentary Turbo
Off (Unlocked) Click Side Switch On (Memory Mode (LMH only)
Off (Unlocked) Hold Side Switch Moon
Moon Click or Hold Side Switch Off
On (except Moon) Click Side Switch Off
On (except Moon) Hold Side Switch Mode advance (LMH)
Moon Long hold Side Switch Lockout (Switch turns red when clicked)
Lockout Long hold Side Switch Unlock
Any (Unlocked) Double click Side Switch Turbo (Really it’s “previous mode then Turbo”)
Any (Unlocked) Triple click Side Switch Strobe

LED and Beam

Unlike other BSS lights, this Thrunite has a Luminus SST70 as the emitter option.  The reflector is still smooth and deep.


As stated above, there’s also a red filter option.

lens cover

Now, here’s the rub for me on this light.  I’ve dialed down the exposure here so that you can see the beam without being completely blown out.  When on Turbo, the output is positively angry blue.  Not only is it angry blue, there’s an emitter issue – like half of the emitter is bad, or something.  It’s partly visible in the beamshot below.  So whatever is wrong here could simply be a bad emitter (hey it happens) or something in the light that caused a bad emitter.  I will probably poke around and see what I can see with a digital multimeter.  I’m open to your thoughts, though!  I don’t mind fixing this one. 😀

blue flower

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

As you can see, the lower modes look “normal” – that is, they aren’t angry blue.  However, the lower three modes look “about the same” (in person they’re visibly different but just barely.  So something seems wrong with the modes, too.  There is no very low mode, for example.

Tint vs BLF-348 ( 219b version) (affiliate link)

Test light is on the left!

I compare everything to the 219b BLF-348, because it’s inexpensive and has the best tint!


What I like

  • Desert Tan is a nice colorway
  • Red filter seems to be very high quality
  • Complete package with high capacity 18650
  • Good user interface

What I don’t like

  • Mine review copy doesn’t work right
  • No non-strike non-colored bezel option
  • Micro-USB charging seems outdated


  • This light was provided by Thrunite for review. I was not paid to write this review.
  • This content originally appeared at  Please visit there for the best experience!
  • For flashlight related patches, stickers, and gear, head over to PhotonPhreaks, another site where I write!
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