This is an all nylon roller assembly used on Likit patio doors. The housing is nylon with a bronze bushing axle for the 1-5/16 inch nylon roller. They are NON-ADJUSTABLE. They slide into an extruded channel inside the patio door's bottom rail. Used by Likit in the 1970's. Each roller has a max load rating of 50 lbs. The two rollers on the door will accommodate a 100 lb. door.