The muzzles have 5 different sizes .There are always having one fit your dog .
S - circumference1: 5.1 inch , circumference2:5.9 inch , Neck circumference:3.9 inch - 10.6 inch
M - circumference1:5.5 inch , circumference2:7.1 inch , Neck circumference:3.9 inch - 13.4 inch
L - circumference1:6.7 inch , circumference2:8.7 inch , Neck circumference:3.9 inch - 13.4 inch
XL - circumference1:7.9 inch , circumference2:11.4 inch , Neck circumference:3.9 inch - 15 inch
XXL - circumference1:10.2 inch , circumference2:12.6 inch , Neck circumference:3.9 inch - 15 inch