Flea collars almost killed our cat

we purchased a Hartz brand flea collar for our adult, male cat. Little did we know that we were hurting him we went to the vet a few months later and they told us to take the flea collar of and we did but my dad kept insisting that the cat did better with it so every time we would take it off and tell him what the vet said he kept insisting that he did better with it and then we went back to the vet and they gave us this site and we showed him all the stories and some of the pictures of TJ. he then looked on our cats neck and sure enough there was a bald raw ring around his neck. WE WILL NEVER EVER EVER IN A MILLION YEARS USE HARTZ PRODUCTS AGAIN!!!!! EVER! thanks to this site you probably saved our cats life