Size: The length of puppy ID collars is 35cm / 13.8inch, the width is 1cm / 0.4inch, and the length is adjustable. Material: These newborn puppy collar are made of high quality nylon and polyester, the soft double-sided fabric gives a softer care to the puppy’s tender skin. Applcation: Suitable for small animals under 6 weeks old, such as newborn puppies and newborn kittens, you can also use them for other small animals such as rabbits, squirrels, etc. Package Contents: 15 pieces Puppy ID Collar, various colors and adequate quantity to meet your needs. Warm Tips: We advise you to wait until the newborns are at least 5 days old before putting on the collar and make sure the collars are on loosely.