Spent some time with the rails from HIWIN over the last couple days. And I can tell you straight up, these things are in a totally different class than the cheap chinese rails found all over the web. Are they on par with the pricey THK's? Time will tell, but I can tell you these things are butter smooth.

I've yet to have any binding on a passive rail that is over 20 inches (500mm) away despite only running a single slide on the passive slide, I bought 2 slides for the passive side thinking perhaps I might need to explore have a wider base on that side for stability, not needed. I've done some pretty high speed jogging and analysis and the drift over the course of them has been less than 50 microns (near perfect). In short, these things are great, definitely keepers.

These are the first rails I have tried that I would feel complete confidence putting into production today. The only knock? They don't have a grease nipple like the THK's, I'm not sure if it is an option on these small 12mm rails either. But for the amount of use that a typical maker PNP system might see it might not be needed.