These are replacements for a blower in a home boiler. The rebuild kit from the manufacturer of the boiler contains the wrong size bearings for my unit. The supplier speculated that it was a design change. There was no other part kit available and no conclusive explanation. VXB to the rescue. . . I was able to replace the bearings for 1/10th the cost of the entire unit (the suppliers only offered solution). This size bearing was VERY difficult to find. VXB has them!