Tape tension pulleys BSR are high precision ball bearings with one or two rows of rolling elements. The outer ring half-cups are made from pressed steel. Due to their low mass moment of inertia, the spindles can be rapidly accelerated up to operating speed. Due to the use of gap seals, friction is low. The pulleys are matched to the normal belt dimensions and mounting conditions. INA Tape Tension Pulley, Plain, Series: BSR, 50 mm OD, 25 mm Face Width, Plastic