Unlike many of the other fabric rolling carriers, this was is roomy enough for my 18# cat. I wanted a carrier that can easily fold up for storage in my small apartment. This has 3 ways of unzipping to place cat inside, plenty of ventilation, 2 good-sized pockets on one side for storage. It comes with a cozy fur insert that can be removed and cleaned, and a duffle-bag type shoulder strap if you prefer to not use wheel base. It was easy to assemble (sides just zip up, zippers are good quality and close smoothly), and thick velcro straps attach to base with wheels. Wheels glide all directions and the handle adjusts like rolling suitcase. The top and side screened openings have a flap that can be used to cover \"window\" if your pet prefers privacy. I doubt this would fit beneath a plane seat, and I would not recommend this carrier if your pet flies in any other compartment without owner present, as there is only a flexible frame built into the fabric. Although the carrier does not collapse or buckle, it will not withstand any heavy object placed on top. Goes without saying, not suitable for feral cats. This is a perfect solution for car transport to vet.