GreaseThey are characterized by excellent water resistance and load-carrying properties and help provide long-term protection against rust and corrosion.Bearing Installation and RemovalBearings should never be installed by pressing on the inner race.Always press on the outer race with a pilot bushing or similar tool, which will only make contact with the metal side of the outer race.A bearing press or similar should be used to exert the force needed to press the bearing into the housing.Ensure that the seating surface is clean and free from rough edges so that they fit true and square.Quite often bearings can feel fine before fitting, but then feel "notchy" or "rough" after fitting. This is almost always due to the bearings not sitting square and true.Care needs to be taken that the bearing is started straight and not at an angle to the housing. Bearing CareTo prolong the life of your bearings, do not direct a high jet of water near areas of your bike where there bearings are located - an ingress of water can lead to premature bearing failure.The material of this bearing is 52100 Chrome steel, Not waterproof.