Keeps grease off trailer wheels. Trailer owners sometimes overfill axle hubs with grease. The Bearing Buddy automatic pressure relief feature will allow the excess grease to escape. While trailering, this grease can be thrown onto wheels. This product fits over the Bearing Buddy to eliminate this condition. Fits: Bearing Buddy® Model: 1980, 1938, 1968, 2047, 2080. 19B outer diameter is 2-1/8".