Ghent's Duo Track Sliding Magnetic Markerboard doubles the useable whiteboard space in your classroom. Two sliding half panels are on a track and move back and forth over a stationary back panel. All three boards are porcelain-on-steel, accept magnets and have a 50-year guarantee. The heavy-duty anodized aluminum frame has a two-inch cork maprail. The two sliding panels glide smoothly on the track on nylon rollers. CustomÃ¢?"sorry, no returns.