SW48AJ:Clearance Adjustable Type Ball Bushing Made in Japan:NB Linear Systems 3" SW48AJ Clearance Adjustable Type Linear Motion Ball Bushing,3" Bore inch type linear motion ball bushings/bearings, inner diameter(bore) is3" inch,high accuracy grade linear bushings, inch series is mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan.