SMSF30WUUE NB Round Flange Double Wide Type Anticorrosion Made in Japan:NB Linear Systems SMSF30WUUE NB Round Flange Double Wide Linear Slide Bush, The retainer material is steel, Bearing is anticorrosion, It is seals on both sides, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), Made in Japan.