Stainless steel bushing
Wear sleeves provide a protective seal running surface and actually become part of the shaft.
The surface of the sleeve is ground to 10 - 25 microinches (.25 - .64 micrometers Ra). The opposite end of the wear sleeve is radiused on the outer diameter to minimize potential seal damage during assembly.
Wear sleeves are cost-effective for original equipment manufacturers that must machine large or complex shafts or spindles to tight dimensional and finish tolerances to provide an adequate seal running surface.
They also reduce the need for complex and expensive shaft matching, repair or replacement.