Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Excellent product

I've had two of these collars for more than two years. I use them almost every day. My dogs do everything with the collars, including swimming. The collars are incredibly durable, both my collars have gouges and scratches.If you follow the training instructions you will very good results with training. Both my dogs were off leash trained in under 2 weeks. Remember though, this is not a punishment device.My only complaint is the remote, its too small. With gloves (winter time) on you cannot push just one button.I originally tried the two dog system, forget about that. You need one remote per dog, you cannot stimulate both dogs at the same time with the two dog system. This is useful when the dogs take off after something at the same time.