Comparison : Item # ER1038, 0.3750 Inch (in) Bore Diameter (d) Extra Thin Open Metric ER Series Ball Bearing
Item # ER1212, 0.5000 Inch (in) Bore Diameter (d) Extra Thin Open Metric ER Series Ball Bearing
Item # ER1458, 0.6250 Inch (in) Bore Diameter (d) Extra Thin Open Metric ER Series Ball Bearing
Item # ER1634, 0.7500 Inch (in) Bore Diameter (d) Extra Thin Open Metric ER Series Ball Bearing