The M4 is one of the largest and brightest flashlights that Surefire makes. It uses 4 SF123A lithium batteries.
SureFire M4 Devastator
Produced
by Surefire
The
M4 is one of the largest and brightest flashlights that Surefire
makes. It uses 4 SF123A lithium batteries.
It can produce:
225 lumens of light for 60
minutes with the MN60.
350 lumens of light for 20 minutes with
the MN61.
500 lumens for 12 minues total (not continuous) with
the N62.
The
version I have has the pyrex (glass) lens, it passes more light than
lexan & will not melt if it heats up.
Older versions have a
lexan (plastic) lens that can melt if it becomes too hot. Lexan
also scratches easier.
The
new "clickie" tailcap switches allow you to press the
button for more conventional on/off
functionality instead of
twisting the tailcap. Momentary lighting is still possible with
the new switch.
The
M4 is longer than the M3, making it easier to hold or even use as a
weapon.
But it's larger size also makes it harder to carry with
you since it will not fit in your pocket
like the others
Surefires I have will.
The
M4 Turbohead can be used on the M3, as long as you use the correct
lamp assemblies!
Comparison photos taken against my
garage door at 20' with 2 M4's: 
The
MN61 has a wider, more diffused hotspot. The MN60 is tighter
but very oval shaped.
The
N62 is very tightly focused and perfectly round at 500 lumens!
Comparison photos taken against my
garage door at 20'
with the M3 (w/MN11
- 225 lumens) for reference:
>
Here
is a comparison between the M3 (Not M3T) at 225 lumens and the M4 at
225 lumens.
Notice how oval the the M4s beam is with the MN60.
Here
is a comparison between the M3 at 225 lumens & M4 at 350 lumens.
The M4 hotspot is bigger and brighter with this lamp assembly
(MN61) and just a bit oval.
This
comparison is between the M3 at 225 lumens & M4 at 500 lumens.
The hotspot is more focused with the N62 and is very intense, but
will eat batteries very fast!
The M4 will only run 2-3 minutes at
a time with the N62 before overheating & is meant
for
tactical entry situations requiring short bursts of blinding light.