1/2" Slide Unit Pillow Block (Inch Series), the innerdiameter(bore) is 1/2" inch dimensions with steelretainer, bearing is a high accuracy grade linear bushings, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan. NB Systems TWD8WUU 1/2" inch Ball Bushing Open Block Linear Motion TWD8WUU Type:Slide Unit Pillow Block Made in Japan:NB Linear Systems Nippon Bearing Linear Systems 1/2" Slide Unit Pillow Block (Inch Series), the innerdiameter(bore) is 1/2 inch dimensions with steelretainer, bearing is a high accuracy grade linear bushings, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan. 687" 1" 2" 3.5" 1.1. 26" 1.688" 2.5.