Have previously talked to a friend who has been with the police. Means that if you, the 15 minute wait complies (ie 15 minutes earlier no longer drink alcohol to advise the police), then the instrument measures almost identical to models of Dräger (Alkotest 6510). We had only 0.01 per mille deviation at 5 measurements! Even my friend was amazed at this precision at this price - TOP of us