4 ball bearings, suitable for Polaris 280 or 180 robot wheel Corresponding model C60 C-60 Dimensions: 1.1 inches outside, 0.43 inches high Plastic bearing body and stainless steel balls, identical to the original, for optimal operation and extended service life. Replacing Polaris bearings on your robot is quick and easy to do yourself Note: The data are all measured manually, please allow an error of 1-3 cm, due to the difference in light and display, there will be a certain color difference, the actual object received shall prevail.