The Trainer is an affordable, easy to use, entry-level backpack dog carrier. Available in sizes XS-L, it is ideal for smaller breeds, dogs that are still growing, training, and learning to socialize. Available in a variety of bright color options, the trainer should be used for short, non-strenuous activities like short walks, hikes, bicycle rides, public transportation, and other similar activities. This carrier fits most comfortably on dog owners with a small to medium build.All K9 Sport Sack carriers are specially developed under the close direction of animal professionals, veterinarians, dog trainers, and outdoor product engineers to be ergonomic, safe, and strong.