This is a top mount bi-fold door guide wheel/cap on a spring-loaded steel shaft in a 3/8 inch nylon housing. The guide cap/wheel is 3/8 inch in diameter with a 5/8 inch lip and is used to fit into a 5/8 inch bi-fold door track.
This bi-fold door pivot is constructed from steel. It features a spring-loaded steel shaft and top mounted design. This style pivot is used on 5/8in. wide track systems.