The material of this sweater is super elastic so you need to choose by the length first

If your dog is prone to biting or chewing

Adjustable Range (lower jaw) : 6

For supervised play only

50% cotton

Smiling Boston Terrier Sweatshirt Size:5XL The material of this sweaterA sturdy and warm sweatshirt bound to keep you warm in the colder months. A pre shrunk, classic fit sweater that's made with air jet spun yarn for a soft feel and reduced pilling. 50% cotton, 50% polyester Pre shrunk Classic fit 1x1 athletic rib knit collar with spandex Air jet spun yarn with a soft feel and reduced pilling Double needle stitched collar, shoulders, armholes, cuffs, and hem SIZE GUIDE LENGTH (inches) WIDTH (inches) S 27 20 M 28 22 L 29