The Red Buffalo Dog Coat is designed to keep your pet warm during colder weather, without compromising on comfort or mobility. With multiple sizes available, this coat works well for a wide range of dog breeds. Please consider the following recommendations when determining which size is best for your dog. Smaller sizes are typically ideal for breeds such as Chihuahuas, Yorkies, Maltese, and Mini Dachshunds. Medium sizes tend to fit dogs like French Bulldogs, Corgis, Pugs, and Beagles. Larger sizes work well for breeds such as Border Collies, Aussies, doodles. Please note some sizes may not fit perfectly as even the same dog breeds vary in size.� However, the adjustable hook-and-loop straps at the neck and chest make it easy to secure a snug, custom fit. They work well even when layering over a harness and it's leash opening allows you to use collars or harnesses without the need to remove the coat.