SWK12UU:Made in Japan:NB Linear Systems Square Flange Type Nippon Bearing Linear Systems SWK12UU 3/4" Bore linear motion ball bushings/bearings, the inner diameter(bore) is 3/4" inch dimensions with steel retainer, Bearing is seals 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.