SWF24GUU NB:Made in Japan:NB Linear Systems Round Flange Type Nippon Bearing Linear Systems SWF24GUU NB 1 1/2" Bore linear motion ball bushings/bearings, the inner diameter(bore) is 1 1/2" inch dimensions with resin retainer, bearing is seals on both sides, bearing is a high accuracy grade linear bushings, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan.