Consult a dog trainer before use. Sizing guide: add 5 cm to the head circumference (including the ears) to determine the collar size. For example, a head circumference of 54 cm becomes 54 cm + 5 cm = 59 cm; in this case choose a collar of at least 59 cm. The choke collar should be placed over the head; its minimum size must exceed head diameter, and avoid a loose fit during active movement. If you have a puppy or a young dog in growth, expect it may outgrow the collar in the near future. Supermarket