Eugene, the PT Snap is a 3aaa light at 3.5 oz, so not ultralight by most standards, but 3aaa is a very popular format and its size is fine in practice. My lingering doubts are about using that style of light with NiMH cells or lithiums (L92) because of differences in the cell voltages. For frequently used lights I believe rechargeables are best, and for long storage I like lithiums.

I obsessed for a while longer today about those two 1AAA headlamps (Manker E02 II and Fenix HL10) but ultimately resisted temptation. Both are electronically switched, and someone measured the Manker's parasitic current at 0.009mA, which is about 78mAh per year, so not suitable for storing with a cell in the light. You could insert a paper insulating disc, but who remembers to look for that if the light doesn't work, especially during the stress of an emergency? It's best to have a light that you can turn on and use immediately.

I decided my Zebralight H50 suffices. It weighs 31g including an L91 AA cell, so weight with battery is about the same as those AAA lights with an L92. The headband is kind of bulky and heavy but I might try swapping it out for an ultralight band made from elastic straps scavenged from covid masks (I'll buy some actual shock cord some other time). The trouble with carrying a headlamp I've found is the strap flopping around and tangling stuff, rather than the weight. So I don't know why the Petzl Zipka style hasn't been more popular. Apparently there was a version of the e-LITE+ that used that system, but they went back to a conventional headband, no idea why.

If anyone cares, the e-LITE+ in a supposedly new 55 lumen version is $30 at brightguy.com. If I had tons of cash I suppose it would be cool to have one, but I'll skip it for now.

Hikerman, thanks for the info about carbide lamps. I always imagined those things as being one spark away from taking off like a rocket ;-).