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 nylon housing. 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 nylon housing. To install, lightly tap them into the pre-drilled top mount holes. Used by a variety of bi-fold door manufacturers.