This is an adjustable top hung, side mounted bracket with a 1/16 inch offset and 7/8 inch flat nylon roller used on the back of a sliding door panel. It fits 3/4 inch to 1-3/8 inch thick doors. Used by a variety of sliding closet or wardrobe doors.
This is a spring-loaded, 11/16 in. diameter nylon roller guide in a 7/16 in. plastic base. It mounts on the top edge of a wood bi-fold door that is 1 in. to 1-3/8 in. thick. Commonly used by Cox as well as a variety of other bi-fold door manufacturers.