Gladys has been wearing your flea collars ever since we rescued her almost a year ago. We have never, ever seen a single flea or tick on her, so I can attest that this product works VERY well! It smells great, and I don't have to worry that she is being exposed to any toxins, since it is all natural. We love it and are very happy with this product! We also have been using it for our cat, Flower, for a couple years now, and it is the same story. Never seen a flea on her! 😊