MOOG 559 U-Joint, 1 Pack Greaseable - allows new grease to flush out contamination and moisture reducing corrosion and wear Needle bearings and snap rings from an original equipment supplier Nitrile rubber grease seals have compressed double lip design for protection from contaminants Consistent heat treatment achieves good bearing hardness for durable wear and strength Bearing cups ground and slightly oversized to fit in a used drive shaft