220V 12V Home Car Negative Ionizer Negative Air Ionization Air Purifier Remove Smoke Dust Air Purifiers Negative Ion Anion Generator Ionizer Difference: single layer only produce negative ion.                   two layer produce negative ion and a little ozone both, ozone concentration is less than 0.05ppm Power: <5W Input voltage: AC220V or DC12V Output voltage: DC-15KV±0.5KV Negative ion concentration: 200 million/cm³ Power cable length: about 1.2m