25mm x 42mm Ceramic Hybrid Front Wheel/Hub Bearing - 25mm x 42mm Ceramic Hybrid Front Wheel/Hub Bearing 25mm x 42mm x 9mm Ceramic Hybrid Front Wheel/Hub Bearing Ceramic Hybrid Bearings have Steel races and Ceramic Balls. In ball form, ceramic is harder than steel and because ceramic balls are non-porous they are virtually frictionless and capable of spinning faster and with less drag than steel balls as well as being more durable.