Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Needs to go back to the drawing board...

There seems to be an inherent flaw in the concept of moving the dial to the air pressure desired and actually having the unit do this.I've now returned two units as the dial didn't work correctly and then unit over-inflated tires.the basic concept is great, just needs more fine tuning. I like the dual power concept and that is the primary reasoned I purchased it in the beginning.