Collar x Height         

XS - 6.5" x 4"   (16.5cm x 12cm)
SM - 8.5" x 6"   (21.5cm x 15cm)
M - 10.5" x 7"  (26.5cm x 18cm)
LG - 11.5" x 8"  (28.5cm x 20cm)
XL - 13.5" x 9"  (34.5cm x 23cm)