Stable, but little air circulation
We used it when our cat was a kitten for trips to the vet. For that, it was okay.
However, and this is important:
DO NOT use it in direct sunlight!
The material absorbs heat very strongly and the air circulation is minimal.
Recommendation: ONLY for short trips, NOT in the sun, and only for very small animals.
Otherwise, the quality is very good. Today, we use it as a sleeping spot in the house, since it's now too small for transport.
The material is good and feels solid and safe. The bag itself is very lightweight.