I purchased this product because my two boxers recently began fighting. After taking a bite to my left arm trying to break up one of their fights, I decited it was time to take control and that this was the safest method to stop them from fighting. I ordered and received a faulty product on first shipment. Plugged in batteries and it worked once and wouldn't work again. Would only make a humming sound near the batteries. I immediately got on Amazon and filed a return. No joke within 15 minutes (and on a Saturday mind you) my phone rang and it was the Owner of the company! He walked me through some things hoping to fix it over the phone. Unfortunately those things didn't work. However, he apologized and advised me he was immediately shipping me out a replacement. I received it Tuesday and it works like a charm! And who says customer service is dead? Give these fine folks an opportunity to earn your business. I have nothing but good things to say. As for the dogs if they even look at each other funny all I have to do is pick this bad boy up and they are immediately in check! So far so good and I have not had to use it. Just let them hear the Zapp and all is well.