Quick, if you had a lip on the base and genesis top piece for the tubing to but up against it would stop the tubing coming off wouldn't it?
I don't understand arjay. The top and bottom caps do have lips. When you look at the pic and see the end/wall of the vinyl tube you are only seeing about half the wall thickness. The rest of the wall thickness is butted up against the lip on the cap. Is that what you meant? The wall thickness is about 1/8". What you see sticking out past the end cap in the pic is just a tiny bit more than 1/16th.