Medium:

• around the neck of the dog (green color on the picture):
  14-22 inch (35-56 cm)
• around the chest behind the front legs (red color on the picture):
  25-36 inch (62-91 cm)

Large:

• around the neck of the dog (green color on the picture):
  18-28 inch (45-70 cm)
• around the chest behind the front legs (red color on the picture):
  30-40 inch (75-100 cm)

Extra Large:

• around the neck of the dog (green color on the picture):
  24,5-34,5 inch (61-86 cm)
• around the chest behind the front legs (red color on the picture):
  38-48 inch (95-120 cm)