In 
Out6x13x5 Ceramic Metal
Product Overview
The Halo ceramic series of bearings are a high quality steel/chrome bearing with metal shields and silicone nitride ceramic balls (Si3N4). These bearings have been tested and proven by many racers.
6x13x5 Halo Ceramic bearing by Avid Racing Concepts is a popular bearing for vehicles/makes like the Serpent, Kyosho, T-Maxx, E-Maxx, Tamiya's, and others. A ceramic can spin at higher rpms with less drag and the life of the bearing is far greater than a steel bearing but in our industry we suggest that you maintain them with oil or grease every half-gallon to a gallon for the longest life possible. Another benefit to ceramics is the weight difference in the balls allowing for less rotating mass. These bearings also come with our newly developed high speed and temp oil instead of grease. So you no longer have to remove the grease. Just put them in and run.
Check your manual for the correct size for your vehicle if you are not certain.
