When i was lookingg for a ramp i was looking for a couple of things. Slope, Easy to move, durability, and adjustability. I found the fold up chairs to do all that. They are very stable, very durable, easy to move (any weight like 5 punds), and you can adjust it from 6''- 3' and with that it changes the slope. The only problem i though it was going to have were the little hole i the folding part but my revo just flys up it. I guess the tires are big enough so roll over and not fall throw. So the chairs really don't have a bad side!