SW24G:Made in Japan:NB Linear Systems Nippon Bearing Linear Systems SW24G NB Systems Ball Bushings Linear Motion, 1 1/2" Bore linear motion ball bushings/bearings, the inner diameter(bore) is 1 1/2" inch dimensions with a resin retainer, bearing is high accuracy grade linear bushings, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan.