Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Effective but replacement batteries are a complete SCAM

The collar works well but the product is designed so that the batteries wear down quickly and it seems whenever I need to use it the batteries are dead. It is an intentional design flaw by the manufacturer to keep you buying their way overpriced batteries.Unless you are superhuman and never distracted and remember to turn the collar off after each use you will lose your mind with frustration.