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