5/16" Inch Flanged Ball Bearing with 1/8" diameter integrated 1/8" Inch (3.18mm) Pin Diameter 1/8" x 5/16" x 3/8" Inch 5/16" inch (7.94mm) Flanged Ball Bearing with 1/8" inch (3.18mm) diameter integrated 3/8" inch (9.53mm) Long Axle, Pin Diameter is 1/8" inch, Bearing Outer diameter is 5/16" Inch (9.53mm), and Width of the assembly is 3/8" Inch (9.53mm Long), Bearing is made of Chrome Steel.