MecArmy SGN3 Keychain Flashlight Review

Official Specs
Short Review
Long Review
  What's Included
  Manual and Packaging
  Build Quality and Durability
  User Interface and Operation
  LED and beam
  Tint vs...
  Beamshots, Runtime, etc table.
  What I like
  What I don't like
Up Next


I’ve had a run of keychain lights lately.  And today I have another one by MecArmy.  I recently reviewed the SGN7, and today it’s the SGN3, a much smaller keychain light.  This one has three emitters (white, red, and uv).

Please check the GearBest 4th Anniversary Sale, too!!  I’m going to be updating the coupon spreadsheet today, too, with great deals!!

Official Specs and Features


There’s really just one version, but four body colors of that version.  They all have the same emitters.  The colors are black, tan, gray, and green.


The price is $42.90.  Going for $32.36 on GearBest right now!

Short Review

It’s a solid little keychain light, and for once, I’m not overwhelmed by the UV of a light.

Long Review

What’s Included

  • MecArmy SGN3 keychain flashlight
  • Lanyard
  • Split ring
  • Manual


Package and Manual

The package is a black printed box with a hang loop, and the usual amount of printing.  GearBest has placed their inventory sticker directly over the picture of the light.

The manual is a small slip of paper printed in English on both sides.  There’s a output/runtime table, a UI description, and a bit of other information.  It’s not the most detailed manual ever, but it works.

Build Quality and Disassembly

This is a nice little light, which feels… quite solid.  I might not normally say something like this, but the pronounced rubber switch takes a bit away from the aesthetic.  A small something, not more.  The light has a great feel in hand.

The sides have a bit of texture – not knurling and not reeding.  It’s most like jimping – well I guess it actually IS jimping. It provides a nice amount of grip.

On to disassembly.  Truthfully I’m not even sure how this light is held together.  The bezel is clearly pressed in but I can’t tell if it’s press fit or held in place with a screw around the switch.  Either way it’s extremely sturdy.


Officially the SGN3 is 59mm long, 23mm wide, and 10mm deep.  It weighs 30g.

This is a very small little light!  On par with the Nitecore Tube, but with three times the emitters, and a metal body!


The body of the SGN3 has a built in loop on the tail.  It’s one piece with the body, and therefore not removable.  This is where the lanyard and split ring connect.


I have found the best place for this light is in my coin pocket, or just deep carry loose.


The SGN3 is powered by a “280mAh” lipo battery.  The cell is not replaceable, and charges via microUSB.  A cable for charging is not included.

I tested the runtime on High (the highest mode, there is no Turbo).  The output isn’t stable, and drops off High relatively quickly.  The claimed runtime is 1 hour, and it’s around 1 hour that the biggest dropoff happens.  The output is at around 60% at this point.  The light only ever switched to Low (or “on but barely”), and never shut off.  I believe the side switch should indicate (red) when the battery voltage is low (but to be honest I can’t remember if this was the case.)


The microUSB port has a rubber cover that actually goes into the port.  When in place, it’s flush with the body (except the little tab that allows gripping).


The charge chart looks good for the cell, charging at just under 1C.  My tests indicate that the battery is in the 330mAh range, which is better than the claim.


User Interface and Operation

Theres a single switch on the SGN3 and it’s a big rubber indicating e-switch.


Here’s a UI table!

State Action Result
Off Press On (mode memory (all emitters))*
Any Hold Mode Cycle (All emitters)
 White Click Mode cycle (M>L>H>Off)
 UV Click Off
 Red Click Cycle (Solid>Flash>Off)

* Mode memory does not include the red flashing mode


Mode Mode Claimed Output (lm) Claimed Runtime Mode Measured Lux
High 160 1h 2690
 Med 59 3h  856
 Low 5 13h  91

LED and Beam

The main emitter in the SGN3 is a Cree XP-G2.  The side emitters are 3mm diameter emitters, one red (620nm) and one UV (360nm).  Only the center emitter has a reflector, and it’s small and smooth.


PWM is noticeable to my eye on low, and marginally noticeable for medium.  Not noticeable on High, though.


Tint vs BLF-348


Beamshots, Runtime, and Lux Measurements

MecArmy SGN3
Emitter Cree XP-G2
Emitter Notes With red and UV
Cell Internal
Glamour Shots Beamshots [0.3″, f/8, ISO 100, 5000k]
Runtime Chargetime
LVP? Switch to Low
Claimed Lumens (lm) 160
Lux (Measured) 48 lux @ 3.173 m
Candela (Calculated) in cd 483.3
Throw (Calculated) (m) 44
Throw (Claimed) (m) 40


Random Comparisons and Competitive Options….

The keychain flashlight market is quite saturated.  This light stands apart by having a full metal body while still being very small, and also having three emitters.  The UV is a nice addition, and welcome.  It’s powerful enough, but not overpowering like some UV.  The SGN3 is the only of the bunch to have UV!


What I like

  • Solid metal body
  • Indicating switch, and big for the body size
  • UV isn’t overpowering, but still useful

What I don’t like

  • Impossible to access internals
  • Key loop adds unnecessary length

Up Next

This week I’ll finish another light, likely one by Rofis.  Stay tuned!


  • This light was provided by GearBest for review. I was not paid to write this review.
  • This content originally appeared at  Please visit there for the best experience!
  • Whether or not I have a coupon for this light, I do have a bunch of coupons!!  Have a look at my spreadsheet for those coupons. It’s possible to subscribe and get notifications when the sheet is edited!!

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