Sizing guide- in a photo gallery.
The K9 Sport Sack AIR® is a great choice for bike rides, shorter hikes, quick trips or any other pet-carrying adventure you can dream up. This classic model is the most flexible, breathable and lightweight pet carrier we offer. Like all K9 Sport Sack® carriers, design and safety come first. The AIR™ was specially developed under the close direction of animal professionals, veterinarians, dog trainers and outdoor product engineers to be ergonomic, safe and strong. 30 LB/13 KG weight limit. 
Ventilated side panels for cooling
Adjustable dual side pockets
Sternum strap with avalanche whistle clip
Moisture wicking, ventilated shoulder straps