Anything produced in quantity will have a certain amount of deviations. I have at least one of all the rails excepting the HUGE one. When I bought my 55 during a recon sale the 1400 that came with the saw was out 2mm on one end from about 18" of the end. I called Festool service and three days later I had a new rail. I check all my rails against 8020 extrusions and used to use one of those extrusions to join my rails with the Makita joiners. After a few years of that I bought my last rail the 3000. It is dead on straight against a 96" piece of 1530 8020, an extrusion flat and straight enough to build CNC machines. I just did a rough count and the nine rails I own excepting the one that was out (it's still in the box) are all perfect against the 8020.