The ball, roller, and needle types of bearings all have similar components. Hardened steel rings called races are either used as an outer race (1) or an inner race (2). Cages (3) provide even spacing for the rolling elements between the races. In some applications, such as the needle bearing shown above, cages are not used and the rollers are in direct contact with the shaft or other mounting. The rolling elements (4) are usually made of hardened steel and are precise for smooth operation. These elements roll or turn to absorb and minimize the friction of rotation.