They have three different size diameter lines, so you can get it for whatever application you need. That's all I've run with and have good results. The only thing I have found wrong with them is that they aren't good for being used as a pressure line from your exhaust. The heat from the exhaust coupler really eats them up.
However, I have found that if you put about a 1/2 inch piece of Shrinkable Heat Tubing over them at the coupler, everything works out great. But if the line does crack/break, that's no big problem. I simply cut off anoter foot of tubing and am back in action. At $0.28 a foot, you can't go wrong.