As I've been looking at info online for various lights, one item I've found is a "thumbswitch dimmer". Unfortunately, they don't give any detail.

I assume it just makes it easy to change it to a lower power. That would be good since, with my present light, to change the power level I have to press a rather rubbery, imprecise button and cycle up through the power levels, back to OFF, and then up again to the lower level I may want. Just not practical on the fly!

But even if the thumbswitch lets you dim it to a lower power level more easily, there is the problem about not know how much it reduces it! Again, looking at my light, it is digital so it holds its light level I set it to until it simply can't anymore, then it automatically drops - but it drops to like 10% all at once - quite a shock if it happens going down a dark hill! Anyway, I'd want a switch that easily dims it, but not that much in one shot.

Either that or some type of easy switch that lets you quickly change levels - not like I have now. If I had that, I could justify a light that doesn't last long enough at full power. Just don't want the switch to be hard to make changes quickly and precisely.