This 1-1/8 inch C-tab tandem roller assembly is designed for Window Master sliding patio doors. It features two concave steel ball bearing rollers in an adjustable stamped steel housing for smooth, quiet operation. The C-tab fits around the corner screw and is captured by the side stile and bottom rail as they are drawn together, providing a secure fit. The housing measures 9/16 inch wide with a 3/4 inch dimple width, 1-1/8 inch tall, and 3 inches long. Rear adjustment allows precise alignment, making it ideal for DIY homeowners and contractors. A Phillips head screwdriver is required for installation.