Let`s see if I remember this right....
The Z2 is a "classic" CombatLight with adjustable grip rings, to allow it to be set up for the most comfortable and secure "Rogers/SureFire" grip.
The D2 is an evolution of the original 6P- no CombatGrip rings, but it does have a pocket clip.
The C2 is a combination of Z2 and D2 to make a light with CombatGrip
and a pocket clip. The grip ring is not adjustable however. Added durability is given by the optional hard anodize coating.
The M2 is the latest in the line and improves on the C2 by adding a shock-isolation bezel to protect the lamp against firerm recoil and the odd drop and bump.
SIS adds bulk to the bezel, unwanted pocket clips can snag on stuff and not everyone likes/needs the Rogers grip capability. Hence for the time being, there is still a place for all four lights- and the original 6P which will certainly live on too.
All models now have the Pyrex lens/lockout tail cap/anti roll as standard however when the variations were originally launched, they may have introduced lockouts or pyrex lenses as an added benefit for that particular model over the others. In time one or two of these may get dropped but who knows what other lights they will have introdiced by then?
