14500 = 14mm wide by 50mm long. The final “0” indicates the cell is in a can.

14500 cells are the same size and shape as AA. However, a AA cell is typically 1.5 volts full, while most 14500 cells use lithium ion chemistry and are up to 4.1v full.

If you put a cell with the wrong voltage in your device it either won’t work or it may damage your device.