... with infrared Anti-counterfeit material. 2,Application methoTo aim the detector head at the item, to press the swith continuously,when ... work, no voice . If the item include moreInfrared material , the detector can work only at distance of 2cm. even the item ... is covered by paper, plastic, cloth etc. the detector can still pass through and detet. 3,SpecificationSize:20 X ...