I have one which corresponds to your description. it works pretty well. Also includes a small flashlight which could be useful (It is hard to have too many light sources).

It fits with my strategy of carrying a bunch of electrons which can be shunted to my phone, various lights, etc, all of which can be recharged from a small solar panel or other source.

According to its user manual, it is good for forty or more lights before the battery needs recharging, assuming no use of the light.

Seems like a fairly useful gadget