I bought two of these to transport my pet birds on a transcontinental flight. The carrier comes with a perch, which is perfect for my parakeets. The wire spacings are small enough that my birds are safe in the cage (small birds can get their head stuck between the wires if the spacing is not narrow enough). Two of these carriers fit very well side by side in an airline-approved pet carrier (the clam shell type), which fit under the seat on a plane. The TSA inspected these cages by hand, did not need to take the birds out, and the whole security check process took only 5 minutes! I was also able to use the feeders I normally use that clip on to the horizontal wires securely. I'm very satisfied with this purchase. It's a simple cage, easy to assemble, and has just the right amount of space for a small pet. Both my birds arrived at the destination safe and sound after this 12-hour journey (first in a car then on the plane then in a car again).