Read down the chain! But since nobody does that, I'll quote it too:

> Regarding Li-Ion cells, you must be cautious. You should buy from trusted sources (e.g. brands) even if they are more expensive or "recycle" old Li-ons by carefully prying open old battery packs from brands that contain these (for laptops etc). > > You need to know another important distinction: There are cells with a protection circuit (against deep discharge, overcharge, short circuit etc) and those without. Read more here: https://www.fenix-store.com/blog/what-is-the-difference-between-protected-and-unprotected-18650-batteries/ Usually cells in battery packs do not have a protection circuit because there is already a protection circuit in the pack itself. > > The tomo powerbanks/chargers have reverse-polarity, deep-discharge etc protection also built in, so protected cells are not necessary by the way. They come without the cells, so there shouldn't be a problem importing these. You can buy new 18650 cells at e.g. e-cigarette store and also stores that sell high-end flashlights.