There are no standard collar sizes so please measure your dog before ordering to ensure the collar fits.
To Measure - Measure your pup's neck with a soft tape measure, pulling the tape snug but not tight (if you don't have a tape measure, use a piece of string and then measure the string with a ruler). Allow sufficient room to slip two fingers between the collar and your pup's neck.
Wide collars are 1.5 inches wide.  
  Neck Circumference Width
M 13-21" 1.5"
L 15-25" 1.5"
XL 18-28" 1.5"