my cat wore this flea collar for 1 month. when i cut it off of her, i noticed the fleas had nested up all around the collar and made my cats neck look like hamburger meat. i am very dissapointed that there is such a product still on the market that has such harmfull effects. had i known of others complaints on this very same product, i would have never bought them. im taking remaing flea powder back to store and demanding my money back, and hatz should have to pay for the treatment for helping the healing process for my cat.