Steel ball bearing 1-1/4 inch diameter wheel.
Housing Thickness 9/16 Fits; Acorn 800 Series, Dorwal doors

Sold each, priced each

Diameter: 1-1/4-inch
Housing Tab Style: Plain Back
Housing Width: 9/16-inch
Material: Steel
Roller Diameter: 1-1/4-inch
Roller Edge Type: Concave
Roller Material: Steel
Roller Width: 5/16-inch
Type: Concave
Width: 9/16-inch

Helpful Article: How to Replace Rollers in an Aluminum Sliding Glass Door