This kit is designed for dogs that work and explore, including K9 officers, search and rescue, service animals, and adventure companions. When these dogs face respiratory challenges from exhaustion, trauma, or high-altitude environments, they need oxygen that's portable, reliable, and ready to go at a moment's notice. Our kits contain everything you need to administer oxygen, including two sizes of our PureVent Pet Oxygen Mask. This product is available for purchase without the need for a prescription from your veterinarian. This kit contains 30 minutes of 99% pure oxygen. You can always add more canisters to your order if anticipate needing more oxygen. *Next Day Air not available for products containing Oxygen Canisters, per O2 shipping regulations, ground shipping only.