A small portable box cage that is used to transport small animals such as a cat, lap dog, guinea pig, etc from one location to another is known as a pet carrier. The two main types of pet carriers are the front openers (generally tough plastic boxes with a metal door) and top openers (these are more like cages with a hinged roof). There are other types available but these are the main ones. All types will have a handle on the top but some will be easier to carry in your arms rather than using the handle. Dog Backpack According to one's specific needs you will find different styles and types of pet friendly carriers on the market. There are special carriers available for when you are traveling by airplane, car, and even ones by a pets weight and size. There are carriers available in backpack, pet car carriers, large or small carriers, sherpa, as well as soft pet carriers. The airplane pet carriers can be used for up to 6 hours at the most when traveling by airplane. If the pet is comfortably accommodated into a airline approved carrier then most airlines will allow travelers to bring their pet on board. If a flight will last longer than 6 hours will safely travel by cargo in a specially designed crate. When flying with a pet airlines usually have some specifications and requirements to make sure that the pet and other passengers travel safe and comfortably. As a general rule the carrier must fit underneath the seat of the owner and must have a waterproof bottom. The crate must also be big enough so that the pet can have enough space to turn around,stand up, and lay down. An airline approved carrier will vary in price depending on the quality, style, and type of carrier. The price range is usually $30-$40 and over $100. The cheaper kennels tend to be metal and plastic. The price of the ones that can be taken into the cabin varies by quality and style. The backpack pet carriers are suitable for small pets and traveling short distances such as by walking. They can also be a convenient for hiking, shopping, and trips to that are taken to the veterinarian. Some models are airline approved so they can be safely used when traveling by plane. They can be very fashionable in appearance because of the variety of sizes, colors, and designs. You can find them at different websites or specialized stores.There are different companies that manufacture the carriers of high quality materials made of microfiber fabric and have extra pockets that can be used for storage. They are usually made for pets that do not weigh more then 10 lbs. Depending upon the quality and style the cheapest backpack carrier may cost up to $50 and one that comes with extra features could reach $100.