Fun Fund Friday post on a Holiday weekend?  Maybe it’s something that you’ll find interesting and give you some reading material over the long weekend.  This is the FourSevens Mini Turbo Mk III modded by SkyLumen, and renamed “Goliath.”  It’s one I’m excited to have and I was very surprised by its performance!  So if you’re not stuck in front of the TV on Disney+ watching Hamilton, read on!

Official Specs and Features

Here’s a link to the official product page at


I’ll consider the Goliath its own thing, and of that there are two options:  Osram W1 and W2.  What I have here is the 5400K W2 version.  Of course there’s the stock FourSevens light, too.


These go for $138 at SkyLumen.

Short Review

Man does this thing throw.  I was super surprised by how much it throws.  The Vinh VN2 driver with the different groups is great, but I’ve stuck with just the 3 mode no memory.  The twist action is very smooth, and the mod work on the emitter is impeccable.  Overall this is a fantastic light, if a little expensive.

Long Review

The Big Table

FourSevens Mini Turbo Mk III Goliath
Emitter: Osram White2 (5400K)
Price in USD at publication time: $138.00
Cell: 1×16340 (included)
Turbo Runtime High Runtime
Switch Type: Twist
On-Board Charging? No
Claimed Lumens (lm) 900
Measured Lumens (at 30s) 774 (86% of claim)*
Candela per Lumen 27.7
Claimed Throw (m) 346
Candela (Calculated) in cd (at 30s) 970lux @ 5.428m = 28579cd
Throw (Calculated) (m) 338.1 (97.7% of claim)*
All my FourSevens 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

  • FourSevens Mini Turbo Mk III Goliath Flashlight
  • FourSevens RCR123A 550mAh cell
  • SkyLumen info/DOB card (+$10) (seen below)

Package and Manual

The package includes the original FourSevens box, but not the manual (sensibly, since that manual no longer really relates to this light.)

The package doesn’t include a manual for the new UI, but that’s available on

Build Quality and Disassembly

I don’t know if Vinh of SkyLumen changes anything regarding the build quality of this FourSevens light.  The other FourSevens lights I’ve had are well built too, but this one seems just better than those.

The twisty action of this light is so smooth.  I don’t normally even like twisties, but wow this one is smooth.  The head is covered in knurling, so there’s plenty of grip for twisting.

The tailcap has a nice big spring.  The head has only a little button, and the two pads that will probably prevent use of a flat top 16340 (but I don’t have any to test).

The threads on the body are anodized, short, and very smooth.  Two and a half turns just turns the light on.

There’s a red gasket in the head, but it’s not a glow gasket.

Size and Comps

Length: 2.38 inches
Body diameter: 0.8 inches
Head diameter: 0.96 inches
Weight (with batteries): 1.8 oz

Retention and Carry

The light comes with a pocket clip which attaches in exactly and only one place.  It doesn’t rotate around the tail, and can’t be reversed.  It’s a very good clip, and hits exactly where it needs to hit.

See below how the clip fits in only one place, and can’t rotate.

This light, and I think all the Goliaths from Vinh, have a magnet in the tailcap.  This magnet is plenty strong to hold the light in any orientation.

Power and Runtime

The Goliath package includes a 550mAh RCR123A cell branded by FourSevens.  It claims to be good enough for High-Drain devices – up to 5C discharge, in fact.  That’s….. 2.75A I believe, but you’ll see below if that’s good enough.

It’s a button top cell.

In the light the cell sticks up like this but it’s no problem to get the head on the light.

Here’s a runtime on Turbo, which per the UI page is described as “100” which we’ll take to mean “100%.”  On 100%, the output looks as follows.  Note that over 1 minute of ~750 lumens is pretty good for a light like this on a cell this size….  The stepdown to 450 lumens happens at just over a minute.  The Turbo timer default is 5 minutes, but as you can see, the light steps down before that, probably based on temperature.  Or it could be a cell issue – the light will draw over 8A on turbo, and a 5C 550mAh cell might not be able to provide that…

High (or “30”) is similarly unregulated as the Turbo.

Once the light has the low output seen above, it will not longer achieve any level of brightness.  So it’ll be clear the cell needs charging, when the voltage is low.  SkyLumen VN2 driver operating voltage only goes down to 2.5V.

Modes and Currents

Mode Mode Claimed Output (lm) Claimed Runtime Measured Lumens Tailcap Amps
100 900 774 >8A
30 270 308 1.21
1 1 ~ 0.01

The light seemed very willing to go over 8A when I was testing it.  I wasn’t willing to push it further, because I think the emitter has already crested in performance well before 8A.

Pulse Width Modulation

Turbo doesn’t have PWM, but the other modes do.  I don’t find it visible.

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

This is a twisty light.  Twist the head for operation.  Tightening it turns the light on, and loosening it turns the light off.

SkyLumen not only changed the emitter, but also installed a new driver – the VN2 driver – in the Goliath.  Details of this are here.  Vinh also made a video, which you can see here.  The UI is somewhat programmable, in the sense that you can pick among quite a few different groups, pick whether you have mode memory (ick) or not), and set the Turbo timer.  Probably even more.

Here’s a basic UI table which covers general operation, but possibly not everything, and certainly not every group!  My mode group is the 3 Mode with no memory.  That’s “Group 9” in the list.

State Action Result
Off Twist (Tighten) On (Low)
On Twist (Loosen) Off
On Twist Off and On Mode advance – You have to be pretty quick here actually – quicker than I was expecting.
On for 2s Turn off/on 8x Enter programming mode (the emitter is flashing between low and mid when in programming)
Programming Mode Twist on/off number of times for desired group Light will blink and memorize group.*

*Note that entering programming mode requires a selection.  IE don’t enter programming just for giggles – you must make a selection.  Turning the light off only causes it to wait for being programmed…

Table out of the way, you can basically get what you want out of this UI.  Here is a chart of the options:

LED and Beam

The emitter is one of the changes done by SkyLumen – installed was a Osram White2 (Osram KW CSLPM1.TG), a tiny 5400K emitter renown for throw.  And this one does throw in this Goliath body.  The reflector is very smooth, and looks deep in this small body but is probably just “normal deep.”  The mod work to install this emitter is very good – you’d pick the light up and think it came this way from the factory.


These beamshots are always with the following settings:  f8, ISO100, 0.3s shutter, and manual 5000K exposure.  Notice that the spot is very much a spot – this tiny light really is a thrower.

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

  • Excellent build quality
  • Incredible throw from a 16340 light
  • UI covers so many bases and is surprisingly easy to program
  • Excellent clip
  • Good finish
  • Mod work is well done

What I don’t like

  • Included cell probably holds this light back a little
  • Programming a twisty with repeated twists is not all that fun


  • This light was provided by me 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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