SMS60GUU-OP Stainless Steel Anticorrosion Slide Bush Made in Japan:NB Linear Systems Nippon Bearing Linear Systems 60mm Stainless Steel Anticorrosion Linear Slide Bush, The retainer material is resin, It is open and seals on both sides, SMS60GUU-OP bearing is a high accuracy grade linear bushings, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan.