Size of collars: 18 inch 26 inch 34 inch 21 inch 29 inch 37 inch 16 inch 24 inch 32 inch 40 inch 19 inch 27 inch 35 inch 22 inch 30 inch 38 inch 14 inch 17 inch 25 inch 33 inch 20 inch 28 inch 36 inch 23 inch 31 inch 39 inch 15 inch