Looking for a solution to discourage your dog from biting, chewing and eating unwanted objects? Size 0000 - Circumference around snout 13 cm 5.1 " , Length (eyes-nose) 3.0 cm 1.2" Size 000 - Circumference around snout 15 cm 5.9 " , Length (eyes-nose) 4.5 cm 1.8" Size 00 - Circumference around snout 16 cm 6.3 " , Length (eyes-nose) 5 cm 2.0" Size 0 - Circumference around snout 17 cm 6.7 " , Length (eyes-nose) 5.5 cm 2.2" Size 1 - ircumference around snout 18 cm 7.1 " , Length (eyes-nose) 6 cm 2.4" More sizes available in our store - please contact us Circumference around the snout, should be measured at the widest point of the snout below eye line in inches or centimeters.To the result should be added extra space to be able to freely open the mouth .