this helps to soften the collar up so it will be more comfortable, and replaces the "alien" smells of the store with the more familiar smells of you and your home.
having a bag of treats or a toy ready, put the collar on your cat or pet fox. leave it on for about five minutes, and have an intense "love the pet" session. treats, toys, ear-rubs, belly-rubs, whatever your pet likes best. then take the collar off and ignore them for the next half an hour. refuse to give them attention of any kind.
put the collar back on, this time for about ten minutes, and once again shower them with 