ISB Self-aligning ball bearings have two rows of balls, a common sphered raceway in the outer ring and two deep uninterrupted raceway grooves in the inner ring. They are available open or sealed. The bearings are insensitive to angular misalignment of the shaft relative to the housing , which can be caused, for example, by shaft deflection.This type of ball bearing is recommended when alignment of the shaft and housing is difficult and the shaft may flex. The outer ring has a spherical raceway and its center of curvature coincides with that of the bearing; therefore, the axis of the inner ring, balls and cage can deflect to some extent around the bearing.

ISB Self-Aligning Ball Bearings utilize two rows of balls and a common, concave outer race to automatically compensate for angular misalignment within a system. Misalignment, either from machining errors, assembly errors, or deflections, are a common risk in precise applications and Self-Aligning Ball Bearings present a viable solution.