This will come down to the quality of the breathalyser and the quality of the sensor contained within it. Breathalysers Australia’s range of fuel-cell electrochemical units are extremely accurate and also read to one thousandth of a decimal point. Our range of semi-conductor units are a little less accurate and read to one hundredth of a decimal point.
When buying a breathalyser always buy a reputable brand from a reputable dealer. If you can’t find information about the make and model through Google then you are not purchasing tried and tested. Also the majority of major brands have had replicated units created of their products. If you want quality assured then you must buy from the manufacturers nominated supplier.