1/2" Inch Ball Bearing with 5/16" diameter integrated 5/16" Inch (7.94mm) Pin Diameter 5/16" x 1/2" x 1 1/4" Inch 1/2" inch (12.70mm) Ball Bearing with 5/16" inch (7.94mm) diameter integrated 1 1/4" inch (31.75mm) Long Axle, Pin Diameter is 5/16" inch, Bearing Outer diameter is 1/2" Inch (12.70mm), and Width of the assembly is 1 1/4" Inch (31.75mm Long), Bearing is made of Chrome Steel.