If you insist on buying second-hand flashlights, there are simple ways. 1, that is, look at the wear marks of hot boots. It doesn't matter if there are scratches, but there is obvious wear and tear, indicating that it is used very frequently. 2, try to flash, flash back to good electricity, for objects about two meters trigger three or four times before starting to call back, indicating that this lamp is used less. The quality of the battery will affect the number of flashes.