Four-Bolt, Square - Normal Duty Normal Duty Flange Bearing Unit Application Four-Bolt Normal Duty Flange Bearings (a product within the Mounted Ball Bearing Unit or "Housed Bearing" family) are one of the most abundant bearing units in use. Flange bearings may be found in a variety of applications, including, but not limited to, agricultural, bakery, construction, forestry, marine and textile equipment. Benefits using Flange Bearing Units Flange Bearing Units are available in a wide variety of styles to suit various applications, with metric or imperial insert options. Their design enables moderate initial misalignment to be accommodated.