SMSF6WUU Round Flange Double Wide Anticorrosion Slide Bush Made in Japan:NB Linear Systems Nippon Bearing Miniature Linear Systems SMSF6WUU Round Flange Double Wide Anticorrosion Miniature Linear Slide Bush, The retainer material is steel, It is seals on both sides, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), Made in Japan.