In my hands on this fine Christmas day is the Cyansky M2 keychain flashlight.  It’s an interesting little light – very tiny, rechargeable, an unusual!

Cyansky M2 keychain Flashlight Official Specs and Features

Here’s a link to the official product page.


Only the version you see here is available.


Like the M3, which I reviewed earlier this week, the M2 is… not easily available.  So I can’t tell you where to buy it, nor can I tell you how much it costs.  Cyansky was interested in a review of it though, so….  I agreed.

Short Review

I can honestly say I did not expect much out of this light.  Lights with built in batteries, Cree XP-G3 (*claimed) emitters, and the like – usually not my jam.  However, there are things to like!  The charging is good.  Beam shape, also good.  What bothers me most about the Cyansky M2 keychain flashlight is that the switch is hard to actuate.

Long Review of the Cyansky M2 keychain Flashlight

The Big Table


Cyansky M2
Emitter: Cree XP-G3 (S4) (claimed – looks like XP-E2 to me though)
Price in USD at publication time: ?
Cell: Internal 200mAh Lithium ion
Turbo Runtime High Runtime
LVP? ?
Switch Type: E-Switch
Quiescent Current (mA): ?
On-Board Charging? Yes
Charge Port Type: micro-USB
Power off Charge Port Low only
Claimed Lumens (lm) 200
Measured Lumens (at 30s) 186 (93% of claim)*
Candela per Lumen 12.7
Claimed Throw (m) 83
Candela (Calculated) in cd (at 30s) 185lux @ 3.259m = 1965cd
Throw (Calculated) (m) 88.7 (106.9% of claim)*
All my Cyansky 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

cyansky m2 keychain flashlight what's included

  • Cyansky M2 keychain flashlight
  • Charge cable (USB to micro-USB)
  • Keyring (not a split ring!)
  • Manual

Package and Manual

cyansky m2 keychain flashlight manual

Build Quality and Disassembly

cyansky m2 keychain flashlight feature photo

The Cyansky M2 keychain flashlight is really just a little blob of a light.  There’s not much going on in the hand – it just feels like a tiny cylinder!

Have a look at the emitter here.  More on this later!

cyansky m2 keychain flashlight emitter

Here’s you first look at the switch, too.

cyansky m2 keychain flashlight switch

And the charge port!

cyansky m2 keychain flashlight switch

Here’s the lanyard hole.

cyansky m2 keychain flashlight lanyard hole

There’s a slight waist to the light; it’s not a completely straight-sided cylinder.

cyansky m2 keychain flashlight printing

cyansky m2 keychain flashlight charge port

The M2 is serialized.

cyansky m2 keychain flashlight on low

cyansky m2 keychain flashlight on low

cyansky m2 keychain flashlight on headstanding

Size and Comps

Officially 34mm x 20mm, and 18.5g.

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.

cyansky m2 keychain flashlight beside torchlab boss 35

Here’s the M2 (right) beside the other Cyansky light I have – the M3.  I reviewed the M3 the other day, here.  Surprisingly the reflector on the M2 is larger than the reflector on the M3 (a bigger light)!

Retention and Carry

Cyansky provides a ring, which is attached to a lanyard, for carrying the M2.  My impression is that this is intended to be worn on a finger as seen below.  The ring is not a split ring!

cyansky m2 keychain flashlight lanyard

Fortunately that little stainless barrel is a screwed-together piece, which makes installing the lanyard on the light simple.

cyansky m2 keychain flashlight lanyard install

Then just screw the pieces back together.

cyansky m2 keychain flashlight lanyard connector

cyansky m2 keychain flashlight lanyard and ring installed

I don’t know if you’d want to use this…. I don’t.  Rather, I’d just keep the light loose in a pocket.  That’s how I carry it, in any case.

cyansky m2 keychain flashlight using lanyard finger ring

cyansky m2 keychain flashlight lanyard

There is no pocket clip, no magnet, no pouch, and nothing else for carry.

Power and Runtime

The Cyansky M2 is powered by a built in lithium ion cell, of 200mAh capacity.  This cell is not changeable as far as I can tell, but it is rechargeable.

Here are two runtimes.  First the highest mode.  It doesn’t quite hit the 200 lumen claim, and the output at 30s is still rapidly declining.  But after the stepdown, the output is still fairly reasonable at around 80-100 lumens.

cyansky m2 keychain flashlight runtime on high

It’s unclear if there is low voltage protection, because the light just kept on and on at around 2 lumens or so, until I shut the test off.  I wasn’t able to disassemble the light to test with bench power.  The indicator beside the switch does indicate when power is low, by flashing red.  This happens under 3V.

The output on Medium is fairly stable, but does trend downward over the course of ~2 hours.

cyansky m2 keychain flashlight runtime graph on medium

As mentioned, the M2 has built in charging.  The charge port has a very flexible press-in cover, which I found very hard to remove.  I even used tweezers on occasion!  (But with tweezers; very easy.)

cyansky m2 keychain flashlight charge port closed

The charge port is micro-USB.

cyansky m2 keychain flashlight charge port open

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

Charging looks very good, and is extremely consistent.  Full charge takes around 1h40m.

cyansky m2 keychain flashlight charge graph

While charging, an indicator beside the charge port is red.  When charge is complete, this indicator turns blue.

Modes and Currents

Mode Mode Claimed Output (lm) Claimed Runtime Measured Lumens Tailcap Amps
High 200 0.8h 186
Med 20 5h 50
Low 5 24h 4

Pulse Width Modulation (PWM)

The lower two modes do have PWM.  It’s not specifically visible but if you saw the beam and though “something could be better” it’s this.

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 Cyansky M2.  It’s an e-switch, on the tail of the light.  Basically it’s what you might call a “fingernail switch” – it’s accessible by more than a fingernail, but only just.

cyansky m2 keychain flashlight switch

The body has just the slightest indentation that will allow a “cover press,” where you can sort of just blindly press with a finger.

cyansky m2 keychain flashlight pwm switch

Here’s a UI table!

State Action Result
Off Click Battery check*
Off Hold (~0.5s) Low
On Hold (~0.5s) Off
On Click Mode advance (LMH)
Any Hold ~1s Strobe (technically Low (if off) then strobe or Off (if on) then strobe)
  • Battery indicator, per the manual:

Green steady (I think the light has been updated to “Blue” however!): 85% power
Green flash: 50%-85% power
Red steady: 25%-50% power
Red flash: >25% power

The UI is very simple and intuitive.  But the switch isn’t really all that excellent to interact with.

LED and Beam

Cyansky claims this to be a Cree XP-G3 emitter.  I have to think that this is a carryover from the M3, which was accurately stated as having a Cree XP-G3, and the manual states such.  What the M2 has is definitely not a Cree XP-G3.  It looks to me most like a Cree XP-E2, but that and XP-G2 are very similar.  Either way, it’s whatever you see below.

cyansky m2 keychain flashlight emitter photo

The emitter benefits from a small reflector.  The beam is quite tight, with a candela per lumen of 12.7.  This light is surprisingly throwy!

cyansky m2 keychain flashlight on low

cyansky m2 keychain flashlight on low

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)

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

  • Charging is very consistent
  • Good beam profile out of such a small light
  • Nice pocket backup light

What I don’t like

  • Mis-identified emitter
  • Not able to be disassembled
  • Cool white emitter
  • Switch is difficult to manipulate


  • This light was provided by Cyansky 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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