About this item M 40 Size: Chest(22"-26"), Neck(15"-17"). Please do measure the size of your dog and compare to the size chart before placing order. Priority reference chest girth. If between 2 sizes,suggest select larger size. If in doubt, write to us and we will help you choose the right size! LIGHTEST JACKET IN THE WORLD - Crafted from nylon fabric with a DWR coating and filled with 1.43 oz of polyester fiber, this insulated dog jacket resists wind and shed water for hours on end without restricting movement or feeling bulky. KEEP DOG WARM AND COZY - Waterproof dog coat is multi-season, and your dog will always be warm and comfortable in it, and you do not have to buy a lot of clothes for your pet. WATER AND WIND RESISTANCE - The winter dog jackets is made of high-quality polyester fiber filling, waterproof, windproof, durable & breathable. Keeps your dog dry and warm even in wet conditions. REVERSIBLE COLORS - Reversible zipper allows you to change from one color to another as desired. The reversible feature adds versatility so you can wear it with different outfits, collars and leashes.