1.FRONT & BACK Dual Expandable Polarized Cat Backpack Carrier for LARGE and Fat Cats up to 20 POUNDS. This cat backpack carrier increase your pet's visual space via front transparent hard shell, Also the front expandable version FIXS VENTILATION & HOT issues vs. non-expandable version. 2.Are you still using the SMALL cat bubble backpack while your little kitten grows up. Your furry friend deserves to own a bigger one. That's the exact intention we add the front extension, 4" extension in front means bigger and roomy inside, fits up to 20 pounds large fat cat. 3.ECO-FRIENDLY AND NON-TOXIC PET-SAFE MATERIALS MADE BACKPACK FOR CATS. Light weight and super wear-resistant shell perfectly against biting and scratching by pets. Entire backpack is less than 3 lbs only. Airline Approved and fits under the seat. 4.TWO CARRYING WAYS. and Wearable shoulder pet carrying carrier backpack with adjustable chest buckle for travel and hiking outdoor activity, the real travel backpack for cats.