Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Not the best.

I tested this unit against a police issue DOT approved Alco Sensor IV. Readings were inconsistent. If you want true accuracy so your reading would match a Police Officers reading... it is imperative you get a unit that contains a fuel cell and is DOT approved.You are gonna pay $450-$750 for such a unit, but how much is a DUI?