That's just a Uni-Strut track, so it's galvanized. The wood door fits into a custom steel frame to prevent warping. Note that it's tough to waterproof (and critter proof) these openings.

We sell barn door hardware. Our tracks are very high quality and have many unique features that make our tracks a great choice! Our tracks have an anti-jump piece to keep your tracks in place and a soft stopper at the end so your door isn't slamming into a piece of metal at the end of the track. Our wheels are specially designed to be completely silent and smooth! We can customize you track length and color to fit your needs. Our tracks are all powder coated and very durable. We are happy to answer any questions you might have!