A Ceramic Concave stainless steel 8 BallBearing. These are replacement bearings with Concave profile and available in ILYY (metric) Size.
A Gold stainless steel 10 BallBearing size C.
A Stainless Steel 10 BallBearing Size C.
A Chrome Steel 8 BallBearing size C "Flat".
A Concave Ceramic 10 BallBearing Size C.
The AIGR Bearing, Aircraft Instrument Gyro Rated, is available in Size C, the same sized used in the General-Yo Entheos, the General-Yo Prophecy or General-Yo Majesty.