Size Measurements  Fit
Small Chest 11-18" x Neck 9-11" Fits Dogs 7-12 lbs
Medium  Girth 14-22" x Neck 11-14" Fits Dogs 12-18 lbs
Large  Girth 18-27" x Neck 14-16" Fits Dogs 18-26 lbs
X-Large  Girth 22-32" x Neck 16-18" Fits Dogs 26-36 lbs