Deep Groove Ball Bearings are one of the most widely used rolling bearings. They are used to accommodate radial and axial loads in both directions. Suitable for all kinds of industrial equipment, micro motor, small rotary motor, office equipment and so on. With small friction and high-limit speed, Uxcell's Deep Groove Ball Bearings are cost-effective and require little maintenance. Carbon Steel bearings are better in toughness than chrome steel bearings after quenching. These cost-effective bearings are widely used in areas with low requirements for Mohs hardness. Single-row, pre-lubricated, normal accuracy. Selection Guide: Shields (Designation Suffix Z/ZZ) - High speed. Protect from dirt and debris. Sealed (Designation SuffixRS/2RS) - Made of sheet steel reinforced NBR (oil- and liquid-resistant). Lower limit speed than Shield Bearings. NOTE： Please refer to the picture and select right type of bearings before your order (Sealed or Shield on BOTH or SINGLE side of the bearing). Suffix on the bearing just for differentiating between Sealed and Shield type of bearing. It would not affect the use of our product. Specification: Model: 684ZZ Shield Type: Double Shield Material: Carbon Steel Cage Material: Stamping Steel Inner Diameter (d): 4mm Outer Diameter (D): 9mm Thickness (B): 4mm Accuracy Class: P0 (ABEC-1) Model: 685ZZ Shield Type: Double Shield Material: Carbon Steel Cage Material: Stamping Steel Inner Diameter (d): 5mm Outer Diameter (D): 11mm Thickness (B): 5mm Accuracy Class: P0 (ABEC-1) Model: 686ZZ Shield Type: Double Shield Material: Carbon Steel Cage Material: Stamping Steel Inner Diameter (d): 6mm Outer Diameter (D): 13mm Thickness (B): 5mm Accuracy Class: P0 (ABEC-1) Package Included: 20x Ball Bearings WARNING: This product can expose you to Lead, which is known to the State of California to cause cancer. For more information go to www.P65warnings.ca.gov.