SMS25GUU Stainless Steel Anticorrosion Slide Bush Made in Japan:NB Linear Systems Nippon Bearing Linear Systems 25mm Stainless Steel Anticorrosion Linear Slide Bush, It is seals on both sides, The retainer material is resin SMS25GUU bearing is a high accuracy grade linear bushings, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan.