Summer of 2017 I had the worst experience with fleas. I live in Pennsylvania and I was treating my house weekly. I spent and wasted so much money on treatments, bombs, sprays, etc. Not anymore. These collars are expensive, but worth it. People have talked about their dogs getting rashes from the collars but my Australian Shepherd has no issues. His breeder uses them on her dogs too and no issues so I'm not sure if maybe the dogs having this problem had sensitive skin or what but the collar caused no problems for my dog or cats.