SW20:Made in Japan:NB Linear Systems Nippon Bearing Linear Systems SW20 1 1/4" Bore linear motion ball bushings/bearings, SW20 inner diameter(bore) is 1 1/4" inch dimensions with steel retainer, bearing is high accuracy grade linear bushings, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan. The NB slide bush is a linear motion mechanism utilizing the rotational motion of ball elements. Since linear motion is obtained using a simple mechanism, the slide bush can be used in a wide variety of applications, including transportation equipment, food processing equipment, and semiconductor equipment. The NB slide bush uses a round shaft for the guide, resulting in effective space utilization, which allows for compact designs. The raceway surface is precision ground. Since the contact surface between the ball elements and the raceway surface is minimized, the NB slide bush provides low friction when compared to other linear motion mechanisms.