... detect pin-sized metal articles. It has an independent battery low voltage hand-held metal detector Function features:* It features ... adjusted according to the on-site requirements.* Indication of low battery voltage (LED light is always on).* It is praise worthy ... .8 cm* Working power supply: 6F22ND 9 V battery (alkaline battery, rechargeable battery)* Alarm modes: sound & light, vibration (switch)