DOG SIZING CHART:
XXS fits 4" through 6" snug neck circumference (3/8" wide)
XS fits 6" through 8" snug neck circumference (3/8" wide)
S fits 8-1/2" through 9-1/2" snug neck circumference (3/8" wide)
M fits 9-1/2" through 11-1/2" snug neck circumference (3/8" wide)
ML fits 11-1/2" through 13-1/2" snug neck circumference (1/2" wide)
Large 13" through 14-1/2" snug neck circumference (3/4" wide)
Extra Large 15" through 16-1/2" snug neck circumference (3/4" wide)
1XL fits 17" through 19" snug neck circumference
2XL fits 19" through 21" snug neck circumference
3XL fits 21" through 23" snug neck circumference
CAT SIZING CHART:
XS fits 4-1/2" through 7" snug neck circumference
Small fits 7-1/2" through 9-1/2" snug neck circumference