Size Chart

Size Description 
Small
8 inches to 12 inches with 5 holes. Each spaced 1 inch apart
Medium
12 inches to 17 inches with 6 holes. Each paced 1 inch apart. 
Large
17 inches to 21 inches with 6 holes. Each paced 1 inch apart. 
X-Large
21 inches to 26 inches with 6 holes. Each spaced 1 inch apart.