Amana Tool® uses only the finest industrial quality precision ball bearings available. Bearings are double steel-shielded for extra rigidity and to inhibit dust. A special high-performance, high-temperature grease is used for maximum life.Note: Solvents should not be used to clean ball bearings, as this will deteriorate the special grease. 'Frozen' bearings (ones that do not rotate freely), should be replaced immediately.