size size range width
small 25 - 31 cm / 9¾ - 12¼" 1,8 cm / ¾"
medium 30 - 38 cm / 11¾ - 15" 2,4 cm / 1"
large 35 - 43 cm / 13¾ - 17" 2,4 cm / 1"
x-large 40 - 48 cm / 15¾ - 19" 2,4 cm / 1"
xx-large 47 - 55 cm / 18½ - 21½" 2,4 cm / 1"
size range is the comfortable circumference of the dog's neck.
 
note: size small can be interchanged between colors on the same size,
size medium to xx-large can be interchanged between color and sizes.
this is due to the difference in width.