Tool AA 2.0. Went to the local outdoors supplies shop to get a new 18650 and happened upon some 14500s. One impulse buy later (lol), I'm taking them for a spin on the only light of mine that takes them.
I'm especially liking the lowest mode, it's just at my favourite brightness level (10 to 30 lumens) and the runtime (at least stated) ain't half bad.