This listing is for 2 piece/s.Single row double groove ball bearing are the most common type of rolling bearing. Their use is very widespread. The racEWay grooves on both the inner and outer rings have circular arcs of slightly larger radius than that of the ball. In addition to radial loads, axial loads can be imposed in speeds and low power loss are required. In addition to open tyre bearings, these bearings often have steel shields or rubber seals installed on one or both sides and are prelubricated with grease.