Sold each, priced each

1 inch steel ball bearing roller unit
Adjustable steel housing assembly
Used by several glass door manufacturers

Housing dimensions: thickness, 5/8 inch; length, 1-1/4 inch; height, 1-1/4 inch; overall thickness, 3/4 inch.
Diameter: 1-inch
Housing Tab Style: F-Tab
Housing Width: 9/16-inch
Material: Steel
Roller Diameter: 1-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