Extra Small Size is for cats under 5 lbs.
Small Size is for most cats under 10 lbs.
Large is for most cats 10 lbs. or more.
Extra-Large is a specialty size for very large cats, typically big-breed males. These cats may start around 20 pounds and range up to 40 pounds or more, with a torso length of at least 18 inches from base-of-neck to base-of-tail. If your cat does not meet the size criteria for XL, you should order large instead.