20" high, 18" wide, 24" long I would say that a pet up to 20 pounds would be fairly comfortable up to the 5 hours recommended to leave pets without potty break. Maybe 30 pound to travel to the vet.
This is as sturdy as most folding crates and is fair as far as appearance. Some pets have been known to squeeze through the seams on the top where they clip to sides, which is dangerous. The top can be reinforced to sides, but if your pet is that desperate to get out they may very well have anxiety issues which much be addressed. Please give your pet the unconditional love that they give you!