Okay, I know about the G-tech LED.
It uses 4AAA in a battery carrier. It has a reverse clickie.
It is approx. 6 1/8" (166mm) in length, with a head diameter of approx. 1 5/8" (43mm). It has a rubber ribbed body sleave, and comes with a lanyard with about a 4 1/2" loop.
It has a large (approx. 7/8") magnifying lense....
It would have an actually pretty decent beam except for...
The image of the bond wires is a BUMMER!
It has some sort of "anti rollers" around the head, and four extension bumps so you can tell it's on face down. It will tail stand to a degree but the lanyard makes it tippy.
Really, seriously if it weren't for the bond wires showing so well, it wouldn't be a horrible light. And even with them, it would keep a Darwin would be from walking off a cliff...
It SHOULD, being only a 5MM LED, be pretty long running on the 4AAA.... But of course AAA ain't nearly the best solution, and a battery carrier is enough to REALLY hack some people off!!!
Edit> It will run on 2AA. But it's pretty dim! <edit