One part covers Span Built™ here: a 22mm adjustable shed door carriage and roller, which also replaces Heritage™ and Absco® rollers. On a sliding shed door that is usually the only part that needs replacing — the leaf and the track are steel, but the small roller carries the whole door, picks up grit and dust, and eventually wears flat or splits, at which point the door drops and starts to scrape or jam. The 22mm in the title is the identifying dimension, so measure the old roller against it before ordering rather than working from the shed brand, and check that the original carriage is the adjustable type with a height screw. Several shed door carriages look alike at a glance; the measurement and the adjustment are what separate them.