Review on Hartz UltraGuard Plus Flea and Tick Kitten and Cat Collar (Pack of 2): Superior Protection for Your Feline Friends by Johnny Pigao

Two of my cats have them and they work. I see other reviews on here about it harming their pets. As with any product, both pets and humans can have allergic reactions. If you notice hair loss, severe itching at the collar site, or other signs of illness in your pet, remove the collar immediately. Also, the flea collar should be loose so the powder gets through all of the cat's hair and not just in one spot. Many wear them too tight. My cats are very allergic to other collars. I started with the expensive ones and they were the worst. I have used Sergeants and my cats have lost their hair. They have no problem with that at all.