This is because they create a tighter seal than traditional hinged doors
Rail is predrilled with 16" hole apart
Pure carbon steel hangers with nylon wheels: Durable and Sliding noiseless
Pure carbon steel hanger rollers -- Sliding quietly and smoothly
The joints are very strong and durable
CCJH 7FT/213CM Heavy Duty Sturdy Sliding Barn Door Hardware Kit -Smoothly and Quietly -Easy to Install Fit 42" Wide Door Panel (I Shape Roller) 14.5FT This is because they createDoor Weight Capacity 330lb, 7FT single barn door hardware kit fits a 1 3 16" 2" thick and 42" wide door, The clearance above the top of the door needs min. 5", The gap between door and wall is 5 8" based on 1 9 16" thick door. Widely Application Main material is steel, sturdy and stable roller rail kit, the bearings run very quietly and smoothly, Passed 150,000 times opening and closing test by doors of meeting room, living room, bedroom, kitchen,