Didn't see much on a search. So I do have a wide set of EDC flashlights of various sizes. However, I like to have a little backup and carry a keychain. It's been a Photon light but they are a total pain to replace the battery. I never have the magic touch to get it right.
I bought an Inox that has three modes and it seems ok.
Any thoughts - the idea is small - not one using a AAA or AA battery.
I keep the light on a chain with a tiny Spyderco. Add my NAA 22S in pocket holster with 5 22 short reloads and I have a lilliputian back up set up.