The size of the dog's neck is totally irrelevant, it is the head size that needs to be measured as per the Blue line, to ensure the Slip Collar can fit over it. Please note that dogs can grow quite quickly therefore checking the size of their neck on a regular basis is key also make sure to take several measurements as the dog may be breathing in while taking the measurement therefore the size will be incorrect.

Sizes Fit Range
10" 5-1/2" To 10"
12" 7-1/2" To 12"
14" 10" To 14"
16" 12" To 16"
18" 12" To 18"
20" 14" To 20"
22" 16" To 22"
24" 18" To 24"
26" 20" To 26"