Ok I think I have most of the M2 Generations plus one proto type. Correct me if I have anything wrong.
1# 1
st Gen*
The Centurion. Logo: Crosshair & Centurion blank on the other side. Old school clip, three flats version, plane Z44 bezel and laser products tailcap.
It's a little controversial some people call it the first C2 but it came with a manual that had "M2 Centurion" on the cover see below. Most people know it as the early M2.
2# 2
nd Gen*
The Millennium Series M2 CENTURION. Logo: Crosshair on one side with Millennium Series M2 Centurion on the other.
Three flats version, old school clip, plane Z44 bezel and laser products tailcap.
Very rare M2 only one other CPF member that I know of has one. Could be more as there are so many SF collector sleepers out there.
3# 3
rd Gen*
The Millennium Series M2 CENTURION. Logo: Surefire on one side with Millennium Series M2 Centurion on the other.
Three flats version, New clip, ribbed shock absorbing plane bezel, laser products tailcap low serial numbers around 6000 &
www.Surefire tailcap on higher serial number.
4# 4th Gen*
The Millennium Series M2 CENTURION. Logo: Surefire on one side with Millennium Series M2 Centurion US patents on the other.
Four flats version, New clip, ribbed shock absorbing plane bezel and some with the caution hot logo,
www.Surefire tailcap.
5# Proto type*
The Digital Series M2D CENTURION. Logo: Surefire on one side with Digital Series M2D CENTURION on the other.
Four flats version, New clip, Different machining on the crown of the body, Mini M3 style shock absorbing plane bezel, Spec's PWN 4VDC 5W. Inductor tailcap.
6# 5
th Gen*
The Millennium Series M2 CENTURION. Logo: Surefire on one side with Millennium Series M2 Centurion US patents on the other
. NOTE: also came out with the new Surefire logo
Four flats version, New clip, New style shock absorbing bezel caution hot logo,
www.Surefire tailcap.
N0:1
No:5
No:2
This Manual came with light No: 1 "Not the light above"
cheers