These bearings are designed with two (2) rows of balls rolling in the outer ring’s spherical surface. The double row of ball bearings compensate for angular misalignment from errors in mounting, shaft deflection or distortion. Under normal conditions, the permissible misalignment of Self-Aligning Ball Bearings is approximately 3°. Perfect for applications requiring extreme accuracy, self-aligning ball bearings with tapered bores of 1:12 are recommended for applications where rigid shaft mounting is a necessity.