... emit 980nm wavelength of invisible light, can detect multi currency with Sound control Infrared(IR) Anti-Counterfeit Detctor Model : HT1 1,Detecting ... ,when the anti-counterfeit material appear, the buzzer will make voice and the greenlight will work on. On the counry, when ... red light work, no voice . If the item include moreInfrared material , the detector can work ...