An insert bearing is a type of rolling-element bearing that consists of a housing and an inner ring with a sphered (convex) outside surface. The rollers (balls) are guided by the cage into the pockets between the inner ring and outer race. Insert bearings are used in applications where the housing bore cannot be used as a raceway for a self-aligning ball or spherical roller bearing, or where heavy radial loads would otherwise require a large-diameter housing bore.