The deep groove ball bearings manufactured by BUT are also available in closed designs, with seals or shields. The seals, which are normally made of acrylonitrile-butadiene rubber (NRB) with a metallic reinforcement, are retained in their correct position by a recess in the outer ring. The working temperature range is from -40 to 100 °C, with a peak of 120 °C for short periods of time.
