TRF20UUE NB Triple Wide Round Flange Pilot End Slide Bush Made in Japan:NB Linear Systems Nippon Bearing Linear Systems TRF20UUE NB Triple Wide Round Flange Pilot End Type Miniature 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.