This product is a practical solution for sliding patio doors. It can replace old or damaged rollers on various types of sliding patio doors, including those made of wood, extruded aluminum, or vinyl from multiple manufacturers. The heavy-duty construction is remarkable. It uses premium dual steel ball-bearing wheels. After a 100,000-cycle test with 2 rollers bearing 265 lbs. it still operates smoothly and quietly. All the bearings are made from heat-treated bearing steel, which is of higher quality compared to carbon steel without heat treatment. Installation and adjustment are a breeze. You can install it in less than 30 minutes using just a few simple tools. The roller assembly has side-leveling adjustment and a minimum collapsed height of 1-1/2 in. It has standard dimensions, with a 1-1/4 in. steel ball-bearing wheel, an 11/16 in. thick housing, and 5-3/4 in. hole centers. The package comes with 2 sliding patio door rollers, and it's advisable to replace both at once. Screws are not included as different doors may require different types of screws.