... useBenefitsMD-300 metal detector is a mini-type hand held metal detector, mainly for security check in important ... indicatorFlashing red LED Alarm Flashing green LED Power onSpecificationOperating frequency,20kHzWeight,272g (including the battery)Size, 420mm( ... Silver ring (1g), 40mm8. Lead brick (1g), 30mmSpecificationOperating frequency,20kHzWeight, 272g (including the battery)Size, 420mm(L)X138mm ...