NB SW8 1/2 Ball Bushings Linear MotionSW8 NB Linear System Nippon Bearing Linear System Made in Japan 1 2" Bore linear motion ball bushing bearing, the innerdiameter(bore) is 1 2" inch dimensions with steelretainer, bearing is high accuracy grade linear bushing,series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan. SW8 NB Ball Bearing Nippon Bearing Linear System Number of ball circuits: 4 Size: 1 2" x 1 1 8" x 1 1 2" inch Inner Diameter: 1 2" inch Outer