Space saving design with a cozy interior: a versatile cat backpack that remains compact when not in use, features a cuddly interior for the cat, and converts easily for home use. It ensures reliable portability in daily life and travel. Quick access and onehanded operation: twoway zip design enables fast entry and exit and smooth handling with reliable onehanded operation at all times. Flexible adjustment and extendable size: extendable cat backpack box with adjustable size and folding frame for space saving storage; variable structure improves adaptability to different cat sizes and usage needs. Active ventilation for comfort: permeable ventilation system with optimized air paths provides refreshing air circulation and comfortable travel conditions inside the backpack. Use scenarios Daily commuting and errands: easy to carry on public transport or in busy environments, with fast access when needed and a comfortable space for the cat during short trips. Vet visits and grooming: adjustable size and folding frame help accommodate different situations, while quick access allows calm handling during appointments. Short trips and travel: foldable design supports compact storage when not in use, and the breathable interior helps maintain a stable, comfortable environment for the cat during outings.