The Surefire L6 is a Digitally-Controlled 5 watt LED flashlight. It uses digital current regulation circuitry
to achieve a constant level of brightness for the useable life it's 3 CR123A lithium batteries.
SureFire L6 Digital Lumamax:
Produced by Surefire
The Surefire L6 is a Digitally-Controlled 5 watt LED flashlight.
It uses digital current regulation circuitry
to achieve a
constant level of brightness for the useable life it's 3 CR123A
lithium batteries.
The L6 also comes with a click on/click-off lockout tailcap
switch and has a combat grip style body.
The L6 is a KL6 5 watt LED bezel on an M3 body, the M3 body has
been relabled "L6".
The L6 has a combat grip body style
enabling you to use this light more comfortably with a handheld
firearm.
The L6 (on the right) has a deep reflector! This gives the
L6 a much more concentrated hotspot than the L4.
The L6 body is the same as the M3 body, so if you already have an
M3, you can buy just the L6 bezel.
The L6 bezel alone is called
the KL6 and will fit the M3/M3T, M4 and M6 Surefire flashlights.
Here are some various beamshots: 
Here are some indoor gym shots at ~80 feet: 
Indoor shots are at ~20'. Outdoor are at
~45'-50': 