Single-row deep groove geometry for high speeds and supporting both radial and axial loads C4 radial internal clearance for radial slack between the inner and outer rings that is greater than CN (normal) and C3 to compensate for thermal expansion Conforms to ABEC 1 precision standard Rubber seals on both sides of the bearing to keep lubricant in and contaminants out Steel cage evenly spaces the balls for even load distribution and prevents contact to reduce friction, vibrations, and noise