Æ MD-SC201A Handheld Metal Detector Technical Parameters: Æ It can detect the location of metal on person, and also work with walkthrough metal detector Æ Radiation frequency 50 KHz Æ Weight: about 250g Æ Power: 9V battery Æ Display: sound/ light alarm Æ Sensitivity: a hatpin can be detected Æ Vibration and buzzer Æ Can use external power supply ( optional)