We don't have specific neck dimensions listed on our sizing guide for the Comfort X Step-In Harness. However, our customer service team would be happy to assist you in obtaining the accurate neck dimensions for this harness.
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1. Live Chat  (click on chat icon on the bottom right corner of your browser)
2. Email  hello@goobypet.com
3. SMS  213.214.01754.
4. Phone  888.445.8011