Size XXS: 4-9 lbs, 3-9" Girth

Size XS:  8-14 lbs, 9-17" Girth

Size S:  12-20 lbs, 18-24" Girth

Size Large: 28-46 lbs, 28-34" Girth

Size XL: 40-70 lbs, 34-42" Girth