This bearing includes our own polymer cage and American made balls. The bearing is double sealed to help eliminate leaks and greased. The bearing fits almost every .21 engine and is the standard size, 7mm x 19mm x 6mm. Specifically made for high RPM applications. Double the RPM capability over steel bearings. Reduce friction,rotating mass. Less vibration and cooler running.
Used and recommended by Ryan Maifield and racers everywhere.