I'm looking on the Surefire web site and trying to decise which of their forearms to buy.  They have three:  618FA, 618FGA, and 918FA.

What are the differences?  

The 918FA seems to have a diffent lamp (the M3 Millenium) integrated into the forearm.  The lamp model used in the other two is not stated.  Anyone know which it is?  How do they differ?

I cannot figure out the difference between the 618 FA and the 618 FGA, either.  Can anyone explain it for me?  Does teh system disable rocker swith really add $160 to the price?????  Is that the only difference?

This situation is complicated by the fact that they use the same darned photo for all three products - bad marketing, slipshod marketing.

The 6xx series are 6 volt and use 2-123A batteries and the 9xx series use 3 batteries and is 9 volt.  Biggest difference between 6 and 9 series is brightness.  6xx series is bright, 9xx series will light a small city.  The 9xx series is approximately 1/3 bigger (length) due to the extra battery.  Personally I chose the 9xx series.
Chris

Is the diameter of the lamp head larger for the 9XX series or is it just longer?  How much longer?

Why is that 618FGA so darned expensive?