The K9 SPORT SACK AIR 2 X-SMALL is designed for dog breeds that weights up to 31 in (79 cm). The K9 Air - X-Small will fit dogs with the length of 10-13 in (25-33 cm) and have a girth up to 23 in (58cm). Typical dog breeds that will fit this size backpack include Chihuahua, Maltese, Teacup Yorkie, Pomeranian and Papillion. Use it as a dog travel bag for hiking, bikes, subways, shopping, motorcycles, skiing, dancing..heck the possibilities are endless! RUFF LIFE: Does your dog suffer from anxiety, depression, or have a physical disability? Or maybe just older or doesn’t have the stamina for your next big adventure. Problem solved! ROUND TALL FAT SMALL: We get it! Dogs come in all shapes and sizes, and we got your dog covered! Available in 4 sizes to fit your yorkie or larger sizes for your chubby frenchie or corgi. Scroll down in the product description to find the right size for your dog! Please contact us and visit our website for more accurate sizing recommendations. SPORT SACK IS THE NEW BLACK: (Tip) For all the chubby dogs out there with a few fat rolls over the collar, our Jet Black is very slimming! Jokes aside, Jet Black is just 1 of the 4 stylish colors we offer in the Sport Sack AIR, and don’t worry all the colors have a slimming effect!