It’s not always the way electronic companies work, but it makes sense that Samsung, which makes and sells the curved Gear Fit fitness tracker, would also make and sell a curved Li-Ion battery.
The Samsung SDI carries 230 mAh of power, which is not a lot compared to a smartphone (2,000 mAh and up is pretty typical) but is rather a lot for wristwear. Now the question is, what other gear — Samsung or not — will this appear in?