ABI Standard Design Cartridge Bearings. OE bearing for Surly Trailer Skewer (BT0009) and Hitch Mount Nuts (BT0019) 90% filled with Mobilux NGLI 2 synthetic grease, dual-lip labyrinth seals If the bearing you are replacing is not marked with a manufacturer number, measure it and compare to specifications listed Item Specifications Bearing I.D. 15mm Bearing O.D. 24mm Bearing Thickness 5mm Manufacturer Number 6802