SMSF20UUE NB Round Flange Type With Pilot End Flange Type Miniature Anticorrosion Slide Bush Made in Japan:NB Linear Systems SMSF20UUE NB Round Flange Type With Pilot End Flange Type, Bearing is anticorrosion, Bearing is seals on both sides, The retainer material is steel, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), Made in Japan.