This is used to replace some new style bi-fold pivot brackets found on bi-fold doors. It is made up of a two piece nylon body with a stamped steel locking plate that locks it into place in the track. Install the bracket 1/2 inch from the door jamb. Once the nylon pivot bracket has been installed into the track, the top pivot Prime-Line part N 6831 on the door inserts into the pivot hole and locked into place as the 2Nd half of the nylon.. See full description for further details