This is a combination set of the bottom pivot and bottom/top guide typically used on a variety of wood bi-fold doors. They are both set a in 3/8 inch diameter plastic housing. The bottom pivot has a tapered grooved tip that fits into the Prime-Line part N 6674 bottom pivot bracket. The 3/8 inch guide is may be used as either the guide pin or as a top pivot depending on the bi-fold door design. To install, lightly tap them into the pre-drilled top mount holes. Used by a variety of bi-fold door manufacturers.it is designed with a positive stop at the ends of the fixed tracks, and because the rear rollers (11/16 in. Dia wheels) on the sliding tracks are fastened to the ends of the drawer-mounted track pieces. These bottom-mount drawer slides can be installed in drawer cabinets with face frames and without. If installing in drawer cabinet with face frame, Prime-Line's model number R-7240 (purchased separately) may be necessary if existing back plates are damaged. The clearance required between the drawer and the drawer opening for these types of slides is as follows: 1/2 in. on left and right sides, 1/4 in. at the bottom and 5/8 in. at the top. Installation instructions are included with each set, and they can also be found within the manufacturer's website.