2 Pack, 1.986″ OD, Bearing Protector Set, With Rubber Cover, Drive In, For Trailer Hubs, Will Fit Any Hub That Requires This Size Cap, Designed With A Grease Fitting Used To Lubricate The Spindle Bearings Without Removing The Caps, Perfect For Boat Trailers That Are Occasionally Submerged In Water, Are Necessary To Protect The Spindle Bearings From Seizing Due To Contamination Entering The Bearing Area Which Will Gaul The Bearing Surface Preventing The Tire From Rotating.