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 life. 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 life. 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 than traditional bearings. All Ceramic Lightning Ultra Seal bearings are packed in grease and will require a short break in period to loosen up.