A few years ago I purchased this bag from Rick Steves website, and I really like it. It fits well under every seat I've had on Air France, Japan Air, Korean Air and Royal Air Maroc overseas. Also good on Southwest, Alaska and Delta domestically. Today I had to mend the velcro on the little RFID bag that fits inside the Bag. It's meant to be securely attached to the inside of the bag, with a secure closure. The velcro is so sticky that the attachments were starting to come loose. I have a lot of experience sewing, so it was easy for me to repair.
Another improvement that I made was to attach an elastic strap to the top front inside of the bag to retain material when the bag is full, and the big top zipper is opened. I had found that without that, things could easily fall out when I needed to access the contents. The bag is accessible when I need to find something during a flight, but it's very annoying to find fallen lost things under the seats!
I usually have a stiff folder that I place in the front of the bag against the elastic band which also serves as a retainer for my stuff. If I found a way to give a review to this bag, it would be 4 stars out of 5. With my homemade improvements, it would be 5 stars for sure.
As I'm writing this, the bags are still on sale!