Just be wary of them as they are likely unprotected cells.
Batteries made for flashlights will have a protection circuit board on it to protect against over & under voltage and sometimes overheating.
Unprotected batteries do not have a circuit board on them and are usually protected by the device that they are installed into.
You can use them BUT you have to be incredibly careful with them as if things go wrong you will be holding what has essentially become a small pipe bomb.