This carrier worked very well for our 13 Lb Boston Terrier The wheeled rack works so well. It Velcros on in seconds to hold the rack onto the soft sided carrier and breezes through the airport effortlessly. So nice to have my hands free. The sides zip down so the pet can stretch out. The sides are netting and pull out. The inside side liner has velcro for easy removal so you use it as a bed liner while the sides are down. My only complaint about this bag is the BOTTOM is far too - soft & flimsy. My other carrier had a much stiffer bottom. I will add something under the bottom padding to stiffen it up. Since it is too soft on the bottom the bottom folds up slightly around your pet while using the carrier only (No rack). The pet sinks in. Imagine a bed mattress where it is too soft and slouches inward around the sides. Easy to fix with something underneath that is rigid. This is only a issue when you actually carry the bag down the plane aisle. I just held the carrier it in my arms to stop the slouch. The carrier is also a little smaller (1\") than most in length. The frame also allows for unzipping at the back to be able to collapse it a little to fit under the seat. Some planes have a box under the seat (Maybe for the video player) and you have to be able to collapse the back to squish it underneath. The airlines won't allow anything at your feet so it must go all the way underneath to the top. The middle seat often has the most space. The aisle seat is usually the smallest. Great carrier but it is small. Also has side pouch. I use carabiner clips to attach the collapsible bowls, water bottle, leash, to the outside.