SMS25UU-OP Linear Slide Bush, It is seals on both sides, bearing is open, bearing is a high accuracy grade linear bushings, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan. Number of Ball Circuits: 5. SMS25UU-OP Type Open Seals on Both Sides Slide Bush Made in Japan:NB Linear Systems Nippon Bearing Linear Systems SMS25UU-OP Linear Slide Bush, It is seals on both sides, bearing is open, bearing is a high accuracy grade linear bushings, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan.