Well, I ended up having to replace the 8 foot traveler from 80/20 with a custom cut one from Open Builds. (O.B. normally only sells 1 and 1.5 meter pieces of V-Slot) Those 'lil white POM wheels that came with the original setup fit the 5mm slot in the 80/20 but you couldn't cut a straight line if your life depended on it. The Extreme wheels from O. B. are a twin bearing setup, and most importantly, they are perfectly Round. Total out of pocket including the extra rail..... just under $200.