Barn Door Roller Assy. The rollers on my hundred year old building wore out. I had 4 rolling barn doors. The wore out door got fixed, and I put off fixing the other 3. Then I sold the building, and just now found the elusive 3! Easy to install, and makes the door as new. Everything you need is in the box. 2 rollers per door, left and right. Adjustment via threaded bolt/carrier