The Biker Helmet is a new and unique pet accessory. They are made with the same plastic used in construction hard hat. Inside padded with sponge to make it comfortable. This lightweight helmets are for dogs and cats who love to travel. Excellent for pet that requires protection from minor head trauma. The Helmet fits pet with 9"-11" head size (around the forehead) and come in with adjustable chin strap. The inside measurement is 3 1/2" wide and 4" long.