The base neck size for each wire gauge is as follows:

2.25mm -> fits up to a 13" neck measurement; designed for use in dogs up to 40lbs

If your dog exceeds the starting length capacity of your suggested wire gauge size, you will need to purchase additional middle links

• This ULTRA-PLUS Training prong collar offers more flexibility between the dog collar and the leash due to the swivel attachment design
• This dog prong collar is one of our more classic versions, perfect for professional dog training purposes.