XS: Teacup & Toy sizes Chihuahua, Pomeranian, Yorkie
Small: Beagle, Westie, Jack Russell, Cavalier King Charles
Medium: Aussie, Border Collie, Dalmatian
Large: German Shepherd, Labrador Retriever, Boxer
XL: Mastiff, St. Bernard, Newfoundland, Great Dane
*Frame is the measurement from one corner of the frame to the other (corner of eye to corner of eye across the face).
*Longest strap measurement is length fully streched.
Please keep in mind that breeds vary by size and that the breeds above are examples, you should go by the size and weight of your dog. The weight and frame measurement are the most important measurements.