I never travel without one. Got mine from Magellans. It is called a sport seat and is under $30. Very light weight. I have had so many people ask me about it, especially in ports on cruises that I think I should start getting a commisssion. The only thing is that when you fold the seat down, you have a 3 legged chair and have to straddle it for stability. But, it holds up to 300 lbs. Think I'll need a few more cruises before I exceed that!