Stainless steel. Dimensions: 5/8″ x 5-1/4″. Fits 4″ roller. Outlasts conventional shafts. Patented design with grease fitting on each end allows rollers to be properly lubricated per manufacturer’s recommendations without the trouble of removing the roller from the trailer. For keel, spool or bow rollers. Includes E-clips. These roller shafts are not pre-greased. Patent # D390167.