Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Worthless

This product did Not work for us. We followed the directions to properly calibrate the device, but when it came to trying to get the breathalyzer to register, it was inaccurate. We tried numerous times, but the device would either not register, or would register a result and then within 5 minutes the result would be drastically different (example from .10 to .04). We decided that a better resource is to use good judgement versus the breathalyzer and Not drive after consuming any more than 1 drink. (We were attempting to see if we would 'know' when our blood alcohol level was above a .08, but the device certainly did not assist with the process.) Maybe a more expensive device would be more reliable. However - Amazon was very prompt about refunding our $30, and the return process was easy.