This 1-1/4 inch plain back tandem roller assembly is designed for Keller, Milgard, and a variety of other vinyl sliding 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 11/16 inch wide and 1 inch tall, with a 1/4-20 threaded mounting hole on the back for secure installation. Perfect for DIY homeowners or contractors, this assembly restores smooth, quiet sliding operation and long-lasting durability to your patio doors.