SMS30GUU-P Stainless Steel Anticorrosion Slide Bush Made in Japan:NB Linear Systems Nippon Bearing Linear Systems 30mm Stainless Steel Anticorrosion Linear Slide Bush, It is seals on both sides, SMS30GUU-P bearing is a Precision accuracy grade linear bushings, The retainer material is resin, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan.