National N131-490 Adjustable Heavy Stay Roller Side Mount – Galvanized. Designed for use as a heavy-duty guide on large sliding doors up to 3-3/4″ thick. Wheel is reversible: can be used from either side of frame. Offers sturdy steel frame construction. Meets ANSI/BHMA A156.14. Manufactured from galvanized steel with Delrin wheel. Includes nail and lag screw holes. Hardened steel bolt for greater strength.