Make sure in get your unit calibrated. Mine wasn't working right. Once I did it was very accurate. I live in MA so you don't dare drive if your over .08 It works and it is what the police use for road test in MA.
We have two units, one for each car. I noticed that one was acting funny after about a year so I sent them to be calibrated. They sent them back within the week and they even replaced the one that had been acting odd with no additional charge.
I have had mine for over a year. I have used it on numerous occasions, and was glad that I made sure I was not driving until my machine registered NO Alcohol.