SW8UU Seals on both sides NB Nippon Bearing Linear Systems Made in Japan SW8UU 1/2" Bore linear motion ball bushing/bearing, SW8UU is Seals on both sides, the inner diameter(bore) is 1/2" inch dimensions with steel retainer, bearing is high accuracy grade linear bushing, series mainly used in the USA, NB brand (Nippon Bearing Linear Systems), made in Japan.