This is a bottom mount pivot used by a variety of bi-fold door manufacturers. The 3/8 in. diameter nylon base houses a 1/4 in. pivot with a hex head nut for adjustment.
This is a bottom mount pivot used by a variety of other bi-fold door manufacturers. The 7/16 inch diameter nylon base houses a 1/4 inch pivot bolt with a unique star adjustment nut.
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 bracket slides to lock it into place.