10pcs Thrust Ball Bearing Miniature High Precision Flat Steel Bearings (F12-21M 12x21x5mm) Features: 1. This ball thrust bearing set features high precision, high speed, and wear small. 2. Small frictional resistance, low power consumption, high mechanical efficiency. 3. High grade steel ball, quiet and smooth rotation at a high speed. 4. Small internal clearance and high machining precision. 5. Suitable for machinery manufacturing, equipment installation and maintenance.   Specification: Condition: Item Type: Thrust Bearing Bearing Material: Bearing Steel F9-20M: Inner Wheel Inner Diameter: Approx. Approx. 9mm / 0.4in Inner Wheel Outer Diameter: Approx. 19.8mm / 0.78in Outer Wheel Outer Diameter: Approx. 20mm / 0.8in Outer Wheel Inner Diameter: Approx. 9.2mm / 0.36in F10-18M : Inner Wheel Inner Diameter: Approx. 10mm / 0.4in Inner Wheel Outer Diameter: Approx. 17.8mm / 0.7in Outer Wheel Outer Diameter: Approx. 18mm / 0.7in Outer Wheel Inner Diameter: Approx. 10.2mm / 0.4in F12-21M: Inner Wheel Inner Diameter: Approx. 12mm / 0.5in Inner Wheel Outer Diameter: Approx. 21mm / 0.8in Outer Wheel Outer Diameter: Approx. 21mm / 0.8in Outer Wheel Inner Diameter: Approx. 12.2mm / 0.5in   Package List: 10 x Thrust Bearing   Note: 1. Please allow slight error due to manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.