Replace or repair worn or broken sliding door rollers with this 1-1/4 inch unique back tandem roller assembly, designed for Milgard and a variety of other vinyl patio doors. It features two concave steel ball bearing rollers in a durable stamped steel housing with rear adjustment for precise alignment. The housing measures 3/4 inch wide, 1 inch tall, and 3-1/8 inches long, with a threaded mounting hole on the back and an optional threaded hole on top for versatile installation. Perfect for DIY homeowners or contractors, this assembly restores smooth, quiet sliding performance. A Phillips head screwdriver is required for installation.