Portable metal detector, convenient to take It can be recharged. It needs 4-6 hours for charging (standard 9V battery, the charger and rechargeable battery are ordered additional) The alarm terms is sound and light alarm simultaneously, or vibration and light alarm simultaneously. You can choose the operate terms optionally When the low sensitivity on-off is pressed, the metal detector will only alarm when it finds big metal object Li battery, USB charge cable (for option) Battery saving function: Automatically power OFF after one minute if no use (for option) Security detecting : Prevent taking contraband, such as : knife, gun and so on Factory : Prevent the loss of valued objects Education area: Prevent taking cheat-tool, such as: telephone, electronic dictionary, and so on