adjustable - suitable for small, medium and large dogs. please look at the photo of the dog size selection instructions.dog tag included - you'll never have to worry about losing your dog with this collar! it comes with an attached qr id dog tag with address and dog documents.durable - dog collars medium is made of high quality wear-resistant nylon. with a sturdy plastic buckle, your dog will be ready for whatever the day brings.safety buckle - providing a strong and reliable grip, the breakaway buckle of these collars exceeds all requirements for strength, safety and comfortable use for you and your pet.reflectible - these collars are perfect for walks at night, to add visibility, and keep up their impeccable look even when they're dirty!