BOX TRACK Hardware for Sliding Doors up to 5,000 lbs.
Amazon.com: SMARTSMITH 6FT Box Rail Hardware Heavy Duty Steel Sliding Barn Door Track, Ceiling Mount Kit, Fit Indoor and Exterior Door, Smoothly and Quietly Easy to Install : Tools & Home Improvement
Amazon.com: DIYHD 6FT Raw Material Galvanized Box Track Sliding Barn Door Hardware for Exterior Barn Door : Tools & Home Improvement
Box Rail Barn Door Sliding Hardware Kit - Interior & Exterior (400 lb) | Bypass barn door hardware, Exterior barn door hardware, Sliding doors exterior
Box Track & More | Leatherneck
National Hardware 8 ft. Plain Box Rail, Galvanized at Tractor Supply Co.