This is a plain back tandem wheel roller assembly that is constructed of a pair of steel wheels and an adjustable steel housing. Each wheel has a concaved (center grooved) edge and features a steel inner race, steel ball bearings and a 5/16 in. roller width. The outside diameter of these rollers is 1-1/4 in. and they are used to replace damaged patio door roller assemblies in sliding glass doors. The housing is 1-1/32 in. tall, 11/16 in. wide and 3-1/8 in. long with a 1/4-20 threaded mounting hole on the back end, and an optional use hole on top. These tandem roller assemblies are used by a variety of patio door manufacturers.Brand Name: Prime-Line Diameter: 1-1/4 in. Length: 5/16 in. Material: Steel Product Type: Roller Assembly Number in Package: 1 pk Hardware Included: Yes Packaging Type: Carded Compatibility: Patio Doors