SMSK6UUE NB Square Flange With Pilot End Anticorrosion Slide Bush Made in Japan:NB Linear Systems SMSK6UUE NB Square Flange Type With Pilot End 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.