For sizing, here how it works: this is an example of you order an 18-inch collar, the measurement will be the middle hole. The collar will have about 1.5 inches of adjustment smaller and larger from the size option you selected. If you have any questions email me. 
 
Love this design but want to customize the colors or hardware? Please email me before placing your order to confirm availability and ensure I can create it just the way you want.
Email - raquelspetsupplies@gmail.com