Size S: width 3/5 inch (1.5 cm) Adjustable collar size 11-13.0 inch (28-34 cm). For example: Shih Tzu 9lbs, Chihuahua 13lbs, Bichon Havanese 12lbs, Maltese 10lbs, Yorkie 13lbs, etc. ADJUSTABLE COLLAR: 5 adjustable metal eyelets keep the leather collar at the correct size. SIZE MEASUREMENT: This is really very important for size measurement. Many customers have placed orders of an incorrect size and fall into inconvenient return and replacement. To save your time and money, please choose a correct size option before ordering. There are Sizes to choose from: 2XSmall: neck circumference 6.3-8.0", neck fit 4.3-6.0", suitable for 2-5 dogs lbs, Xsmall: neck size 8.6-11", neck fit 6.6-9.0", suitable for dogs 5-11 lbs, Small: neck circumference 11-13.0", neck adjustment 9.0-11.0", suitable for 10-16 pounds dogs, Medium: neck circumference 12.5-15 Large: 14.2-17.3" neck, fit 12- 15.0", suitable for dogs 19-28 lbs(even though this size was named large, in fact, it is not suitable for large