Instruct: Classify Amazon reviews into positive or negative sentiment
Query: not great

too large a head for all but the largest dogs...just puts out ions fr small hole....[poorly designed on/off button that easily gets turned off while using and also turned on when not....have accidently used up several 9v batteries when somethig touched it in the drawer and turned it on...........would buy one of the other models if had it to do over.