SureFire M2 Conversion
I converted my C2 HA to an M2.
Produced by Surefire

This is a Surefire C2 that has been converted to an M2.
 
 

Step 1: Replace the stock C2 bezel (shown above) with a shock isolated M2 bezel.
Step 2: Remove the tailcap and add an extra o-ring for a total of two (if you don't already have two),
this makes it waterproof.  The M2 bezel & extra o-rings are available from Surefire.
 
 

The M2 is a more rugged and watertight version of the C2.  They both use the same
lamp assemblies P60 (65 lumens) & P61 (120 lumens), but the pyrex lens in the M2 bezel will not melt
from the heat generated from the P61.  It is possible for the lexan lens used on the C2 stock bezel to melt!
Note: Earlier versions of the C2 bezel used a lexan lens, current versions include a pyrex lens.
 
 

This is how the M2 sizes up with the Streamlight Scorpion & the SureFire M3 & E2.
 
 

This is how the M2 with P61 compares to the Streamlight Scorpion.