Mogli went through several brands and types of collars and managed to get every one off (and chew it up) within days. Sometimes he wrecked two in a week. He'd use the tags to pop the clasp, slide along the balcony net to snag the adjustable collar slide and pop or break the clasp or pull the collar off, etc.. In desperation, I finally tried Beastie Bands, which are very stretchy and have a Velcro clasp. He likes them and doesn't even attempt to remove them. I don't think they'll hold up very long, but they're inexpensive. He's got a Boomerang slide-on tag, too, which doesn't annoy him and he can't use to remove the collar.If anyone has a brand they can recommend please post them? The ones we were getting at PetSmart, and similar were of no use.