The REI duffel I use is very sturdy and packs down, but it doesn't pack down super small. I carried it with me on a trip last year, and it was a pain figuring out what to do with it. I knew I'd be needing the duffel to hold my gear when I boarded a train at the end of the trip. Otherwise I would have found a way to send it home. But it remains a decent way to take my gear on plane. [MENTION=156952]Doug64[/MENTION]'s method looks like it packs a lot better, though.