This bi-fold door guide wheel is constructed from nylon and comes affixed to a steel base. It features a top mount spring-loaded self-adjusting design. This guide wheel fits 1 in. to 1-3/8 in. thick bi-fold doors up to 30 lbs. each.Nylon wheel, steel baseTop mount spring-loaded designWhite in colorFits 1 in. to 1-3/8 in. thick bi-fold doors30 lb. carrying capacityFor further dimensional information, please see the line drawing