... time, the sound has high-frequency tone when detects big metal object;The sound has lower frequency tone when detects small ... tool for safty-checking, convenience using. It could be detected metal accrately, using place:airport, court, education department,prison, stadium, ... AE.run.minisite.productShow(); oProductShow.init( { 'aImgSrc': aBigImageSrc } ); } )(); Hand-Held Metal Detector GC-1001