RC Car & Truck Ceramic Lightning Ultra Seal Bearing kits are specially designed for on-road or relatively clean driving environments. These ABEC #1 bearings are maintenance free and lubed for the life of the bearing. The Ultra Seal is a non-contact, frictionless seal that is placed beneath the metal shields so they are still considered maintenance free and lubed for the life of the bearing. The non-contact seal eliminates any drag typically associated with a rubber sealed bearings and still provides extra protection against external elements. Ceramic hybrids are lighter, have less rolling resistance and can sustain higher operating temperatures.