Weltool W4 “Dragon in Clouds” LEP Flashlight Review

I finally got a LEP!  This is the Weltool W4 and it’s a fantastic option in the LEP field…  LEP (Laser Excited Phosphor) lights are just pencil thin beam massive throwers – limited output (this one’s around 560 lumens) but throws a massive claimed 2.6km!!!  I’m super pleased to be able to present this review for you and thanks to Weltool and KillzoneFlashlights.com for sending this one over for review!

Official Specs and Features

Here’s a link to the official product page.


There’s just the one version.


This light lists at $306 and that’s generally what you’ll end up paying for it.  It’s fairly rare, sells out fast, and will be limited availability.

I recommend you buy this at KillzoneFlashlights.com – they’re the one who supported me by sending this light, and they’re great people!  Here’s a referral link so they’ll know who sent ya!

Short Review

This light is every bit as impressive as I figured it would be.  It’s every bit as impressive as you’ve heard it is.  It’s going to blow your mind for throw.  That said the use case for this light is as narrow as the beam.  I can’t think of a scenario where I’d need it.  Except – that is – for showing to both of my friends.  This and the Imalent DX80 would be like a 1-2 combo of incredibleness.

Long Review

The Big Table

Weltool W4
Emitter: LEP
Price in USD at publication time: $306.00
Cell: 1×21700
Turbo Runtime High Runtime
Switch Type: Mechanical
On-Board Charging? Yes
Charge Port Type: USB-C
Power off Charge Port with no Cell?
Claimed Lumens (lm) 560
Measured Lumens (at 30s) 398 (71.1% of claim)*
Claimed Throw (m) 2670
Candela (Calculated) in cd (at 30s) 4570lux @ 20.174m = 1859946cd
Throw (Calculated) (m) 2727.6 (102.2% of claim)*
All my Weltool 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

  • Weltool W4 Dragon in Clouds LEP Flashlight
  • Weltool 21700 with USB-C Charging
  • Spare o-ring
  • Charge cable (USB to USB-C)
  • Manual etc

Package and Manual

This warning is front and center.

The warning also features prominently in the manual.

Build Quality and Disassembly

The build quality of the W4 is top notch.

I might describe it as “overbuilt” since it’s beefy throughout the body.

The knurling is diamond pattern and not overly aggressive.

The lights are serialized, too.  The Class 3B Laser Product is also posted on the head.  Let’s talk about the Class 3B warning for a second…. if this was “really” a Class 3B Laser Product then there should be some kind of mechanical lockout (I think, I’m no laser expert) (and the mechanical switch does not count.)  That’s not to say it’s not a real Class 3B laser product, but it’s more likely that it’s not following that guideline by the FDA.  If that’s the case then you might consider the fact that these lights could get pulled from the shelves….

The threads are very smooth.  Anodized, square cut, but fairly long.  I count 4.5 turns to tighten.

The switch can be maintained, too – just held in place with an aluminum retaining ring.

The cell tube also separates, but is not reversible.  Those threads (on the head) are not anodized, but are shorter.  I didn’t find them as pleasant to unscrew, so I’d rely on the tail cap.

Also (above and below) look at the driver retaining ring.  It’s beveled, which is fairly uncommon for this rarely-seen detail.  It’s a nice touch!

Both head and tail have springs.

Size and Comps

Size (±0.5mm): (head diameter) 60.5mm, (body diameter) 27mm, (length) 193mm
Weight: 332.8±0.5g (without battery)

It’s not really a short light.  But at the same time I really have no frame of reference for what’s going on inside the light, … maybe these just have to be that long for the LEP to LEP.

Here are my two Weltools – T11 and W4.  Very similar in size and shape!

Retention and Carry

Provided is a pocket clip but let’s call it a “belt clip” instead.  It’s a friction fit clip with very good grip strength and should be perfectly reliable.

Power and Runtime

The W4 is powered by a single lithium ion cell.  The package includes one, which is a 5000mAh cell (called the “UB21-50”).  The cell has built-in USB-C charging, and an indicating light right in the center of the anode.

That cell isn’t required though – the W4 worked successfully on some random 21700 cells I have on hand, including a flat top unprotected Imren.  And just about any 21700 should work fine, because of the dual springs and relatively low current requirements even on High (around 3A).

The cell goes into the light in the normal way: positive toward head.

Here are a couple of runtimes.  It’s a two mode light, so this is a runtime for every mode! 😉

I have never experienced a light like this before, nor have I tested one so it’s hard to say that my lumen tube works perfectly with this setup.  That said, the reasonableness of the numbers makes me fairly confident in both the light and my setup.  I wouldn’t worry that the 30s value of 398 lumens is lower than spec – throw at 30s is better so it’s all a wash.

There are a number of stepdowns, and then the light starts flashing (main emitter/only emitter) (which you can see in the runtime).  Then the light switches off at around 3V.

The low runtime is properly boring and extremely well regulated, until the shutoff.

On bench power, at around 2.9V the emitter flashes a few times as warning, and then the light switches off.

The light ships with a charge cable, which can be seen below.  USB to USB-C, and fairly short.

Charging looks good but is a bit slow – I’d expect 2A or so for a big 21700 cell.  Still it looks good though.  Consistent = good.

Modes and Currents

Mode Mode Claimed Output (lm) Claimed Runtime Measured Lumens Tailcap Amps
High 560 1h58m 398 2.71
Low 187 4h32m 139 0.87


No PWM at all.

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’s a single switch on the W4.  It’s a forward mechanical clicky.

The switch is extremely proud and easy to access.

Here’s a UI table!

State Action Result
Off Tap Momentary High
Off Double Tap Momentary Low
Off Click On (High)
On Click Off
High Double Click Low

The UI is of course very simple.  Just two modes on a forward clicky.  The FW clicky allows momentary which is great.

LED and Beam

“LED and Beam” might not really fit here.  It’s a LEP, which means Laser Excited Phosphor.  Despite how the front of the light looks below, it is actually flat (the domed glass is covered).

These beamshots are always with the following settings:  f8, ISO100, 0.3s shutter, and manual 5000K exposure.  Note that these are taken from the same distance as always, so the beam realllllllly is that much of a pencil thin beam!!

And here are some other/more/outdoor beamshots, not all of which are at the above camera settings (but they’re logged on the photo.  Grouped in sets by location.  I’m sorry but outdoor shots are not my thing – I both find them very hard to take effectively, and also do not find them useful at all.  I matched the camera settings to generally what I was seeing in person.  I’ve included some control (dark) shots, and some shots with another random light I had on my person (Skilhunt M200), and of course, Giggles.  In many of the cases below, Giggles is much more useful.  But at at the longest distance shown (290m) we’re only stretching the legs of the W4 – it reaches 10x as far willingly.

And a couple of randos, just pointing at the ground in shaded daytime:

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

Test light is on the left!

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


What I like

  • LEP lights are just incredible.  This one is too
  • Nice attention to details on the build
  • Meets specs on throw
  • Complete package including cell
  • USB Charging is good

What I don’t like

  • I’d love to see a 18350 version
  • The LEP beams are quite green.  I’d settle for less throw and some better tint.


  • This light was provided by Weltool via KillzoneFlashlights.com for review. I was not paid to write this review.
  • This content originally appeared at zeroair.org.  Please visit there for the best experience!
  • For flashlight related patches, stickers, and gear, head over to PhotonPhreaks, another site where I write!
  • Use my amazon.com referral link if you’re willing to help support making more reviews like this one!

Author: zeroair

Leave a Reply