Self-Aligning Ball Bearings Open TypeSelf-aligning ball bearings have two rows of balls and a common sphered raceway in the outer ring.
The bearings are insensitive to angular misalignment of the shaft relative to the housing. 
Self-aligning ball bearings generate less friction than any other type of rolling bearing, which enables them to run cooler even at high speeds.

FOS self-aligning ball bearings are available in several designs, including:
1.basic design bearings 
2.bearings with an extended inner ring 
3.sealed bearings