Right now, just five. That's all they had in stock. I plan on picking more up as soon as they come in. I don't think they will touch, but if they do, the four outside ones can be milled down a bit (just on the "flanges").
I think what I'm going to do is get more rollers, then mill out a better mount for them. That way I know for sure all are trued up real good. When that happens, I'll post some pics and the results.
I won't use it all the time, but it'll be nice to have when I need it. Also need to make one for 3/8" aluminum tubing.