Heavy Duty Construction: Premium dual steel ball bearing wheels still work smoothly and noiselessly after a 100,000 cycle test with 2 rollers bearing 265 lbs. While others may use the bearings made from Carbon Steel W/O heat treating, we insists all bearings made from Heat Treated Bearing Steel.Easy to install & Adjust: Easy to install in less than 30 minutes with a few simple tools. This roller assembly features an end leveling adjustment with a Phillips head screwdriver.Standard Dimension: Heavy duty 1-1/4 inch steel ball bearing wheel with 11/16 inch thick housing and 5-3/4 inch hole centers. For further dimensional information, please see the line drawing.Package Includes: Includes 2 pack of sliding patio door rollers, we recommend replacing both rollers at the same time. Screws NOT included, please kindly reuse the original ones.Replace Old or Damaged Rollers: Commonly used to replace rollers on vinyl or wood patio sliding glass doors manufactured by Guardian, Craftsman, MI Windows, Aspen, Associated Materials, Croft, VinylMax and others.