Alfie Pet by Petoga Couture - Kelson School Uniform Jumper Size Medium best fits neck girth: 11", breast girth: 14", and body length: 12". Sizing for each dog is unique. We highly recommend you measure your pet precisely with a flexible tape measure to ensure the best fit. Contact us if you have question. We are happy to help. This two-piece jumper and scarf is made for comfort, style and will stay put. Easy to put on and comfortable to your little baby. Great for every day walks and weekend party. Try one on your doggie today!