This is a combination set of the top pivot and top guide typically used on a variety of wood bi-fold doors. They are both spring-loaded steel shafts set a in 7/16 in. diameter steel housing. The pivot fits a 7/16 in. diameter bore, and the pivot stem measures 1/4 in. The top guide wheel fits on 7/8 in. wide track systems. The 7/8 in. horizontal roller on the guide provides a smooth guiding of the lead door. The top pivot has a 1/4 in. diameter pin set in its steel housing. To install, lightly tap them into the pre-drilled top mount holes. Used by a variety of bi-fold door manufacturers.