At COVONO, we focus on taking perfect care of your pet and are committed to providing you with something different, something better. The COVONO Expandable Pet Carrier Backpack comes with rear expansion design, large transparent acrylic window and super ventilated system, is designed to keep your pet protected, secure and comfortable when you are out with your pet, such as routine trips to the vet, travel, hiking or camping. 360° Airflow The 3 sides of the backpack come with 3 mesh windows and 9 venting holes, to keep the air circulating and fresh. Your pet can breathe freely and stay comfortable. Expandable Space With the expandable design, the space inside the backpack can be doubled. The expandable part uses stable steel frame, can bear load without deformation. 4 Entrances The backpack features front, rear and side openings, which allow for effortless entry and stress-free loading. Ergonomic Design It provides adjustable padded shoulder straps, sternum buckle and waist buckles, to reduce the burden on shoulders and maintain the stability during travel. Improved Mat The hard wooden board inside the cozy fleece mat can enhance the stability of the base while the large Velcro ensures the mat can be kept in place easily, no need to deliberately adjust the position of the mat. Transparent Window It features a large transparent acrylic window, which is perfect for your pet to look out and for you to check on your pet (tear off the protective films on the both sides of the acrylic board before use). Attention: Measure your pet before purchasing. Do not select the backpack size based on weight only, please reference your pet's length and height in selecting a backpack size.