Small: Fits small, toy, and miniature breeds including puppies. 25-40 cm / 10-15 in.
Medium: Fits small to medium breeds like Jack Russell and Cocker Spaniel. 30-50 cm / 12-19 in.
Large: Fits medium to large breeds like Poodles or Collies. 40-60 cm / 16-21 in.
X-Large: Fits Large to X-Large breeds like Retrievers and Shepherds. 45-65 cm / 18-26 in.