One part is listed to suit Heritage™ shed doors: a 22mm adjustable shed door carriage and roller, which also replaces Span Built™ and Absco® rollers. A single-part range is a plain answer in itself, because the carriage and roller is what fails on a shed slider. The wheel runs in thin rolled steel track full of grit and eventually flat-spots or seizes, at which point the door drags on the floor and pulls out of square. The adjustment on the carriage is what lets you bring the door back to plumb once the opening has settled. Measure the roller at 22mm across the wheel before ordering, as shed door carriages from different makers look alike and come in several sizes, and the diameter is what separates them. Check too that it fixes to the door the same way yours does.