This is a top mount bi-fold door pivot that is typically used on Acme and Cox bi-fold doors. The spring-loaded 1/4 inch steel pin inserts into a pre-drilled hole in the door and the top pivot bracket above, creating a pivot point for your bi-fold door. Each steel pin is self adjusting and features a mold injected white plastic base. Use with the Prime-Line parts N 6546 and N 6547 for bottom pivots (purchased separately) for best installation results.