I tried to find a muzzle for my 3-years-old dog that thinks other dogs exist to put her teeth in as soon as possible. I think we will cope with socialisation - as she always gets on well with my second dog - so I need a muzzle but I couldn't find anything to fit her and prevent her from taking it off at once. But this muzzle still allows her to open her mouth and put out her tongue, but doesn't let bite at the same time. So I am happy with it. You can't beat this web-site for customer support and help. I am run out of words to describe how I recommend it!