Spherical roller bearings typically consist of an inner ring with two raceways inclined at an angle to the bearing axis, an outer ring with a common spherical raceway, spherical rollers, cages and in certain designs also internal guide rings or center rings. The design of these bearings means that they are naturally self-aligning and can handle very heavy radial and axial loads at moderate speeds. The internal design of these bearings is not standardized by ISO, so it varies between different manufacturers and different series.