Single-row deep groove ball bearings are the most common type of rolling bearing. The raceway grooves in the inner and outer rings form a circular arc with a radius slightly larger than that of the balls.
In addition to open varieties, these bearings may have steel shields or come pre-lubricated with grease maintained by rubber seals installed on one or both sides. Snap rings are sometimes used on the outside diameter of the outer ring.
Cages are generally made of pressed steel, though large bearings and bearings designed for high-speeds may use machined brass cages.