Need help finding the perfect fit? XS: 4.5lb/2kg - SMALL PUPPIES AND NEWBORNS S: 9lb/4kg - AFFENPINSCHER, BOLOGNESE, CHIHUAHUA, JAPANESE CHIN, MALTESE, NORWICH TERRIER, PAPILLON, POMERANIAN, YORKSHIRE TERRIER M: 17.5lb/8kg - APSO, BORDER TERRIER, ITALIAN GREYHOUND, JAPANESE TERRIER, MINIATURE DACHSHUND, MINIATURE PINSCHER, MINIATURE POODLE, NORFOLK TERRIER, PHALENE L: 33lb/15kg - BOSTON TERRIER, CAV KING CHARLES, DACHSHUND, FRENCH BULLDOG, JACK RUSSELL, MINIATURE SCHNAUZER, PUG, SHELTIE, SHIBA INU, SHIH TZU, WESTIE, FOX TERRIER XL: 44lb/20kg - BEAGLE, COCKER SPANIEL, CORGI, ENGLISH BULLDOG, KELPIE, SPITZ, STAFF BULL TERRIER, SCHNAUZER, WHIPPET 2XL: 55lb/25kg - AUSTRALIAN CATTLE DOG, AUSTRALIAN SHEPHERD, BASSET HOUND, BORDER COLLIE, SAMOYED 3XL: 77lb/35kg - AMERICAN STAFFORD, BOXER, BULL TERRIER, COLLIE, DALMATIAN, GOLDEN RETRIEVER, GREYHOUND, LABRADOR RETRIEVER, POODLE, SIBERIAN HUSKY 4XL: 100lb/45kg - AKITA, BERNESE MOUNTAIN DOG, BLOODHOUND, DOBERMANN, ENGLISH MASTIFF, GERMAN SHEPHERD, GREAT DANE, NEWFOUNDLAND, ROTTWEILER, SAINT BERNARD*Note: these recommendations are based on average dog breed sizes. Is your dog larger than average, or are you unsure about the size? Choose one size larger than stated above. Satisfaction Guaranteed We understand there’s only one opinion that matters above all, that of your own fluffy friend.That’s why MrFluffyFriend™ gives you a 30-day satisfaction guarantee, so your pet can experience the benefits of living an anxiety-free life.If you or your fluffy friend decide it’s not the perfect fit, a full refund is assured!