Here are the sizes for reference!
XS 15.7x20.9x3.1 in Recommended for dogs like Chihuahua, Yorkshire, Griffon, etc.
S 20.9x27.6x3.9 in Recommended for small dogs like Pug, Pomeranian, Maltese, etc.
M 27.6x27.6x3.9 in Recommended for medium for dogs like Beagles, French Bulldogs, Dachshunds, etc.
L 27.6x39.4x3.9 in Recommended for big dogs like Golden Retriever, Dalmatian, Goldendoodle, etc.