It's for the bike lights that I have been using for many years, but today the USB charging port snapped off, and there's no way I'm going to be able to solder this surface-mount piece of shit back on. The company went out of business several years ago, and even their domain has been squatted, so I can't ask them. (So their "lifetime guarantee" turns out to have meant "three years".) I would rather buy a new battery than switch to a new model of bike light.
(By "battery" I obviously do not mean the battery part, but the whole assembly.)