A rolling-element bearing, also known as a rolling bearing, is a bearing which carries a load by placing rolling elements (such as balls or rollers) between two bearing rings called races. The relative motion of the races causes the rolling elements to roll with very little rolling resistance and with little sliding.

You're talking about the uncertainty of the bearing.

It varies with the design of the sonar equipment.

What about it?

Bearing children and caregiving relates to reproductive work

Here is a website that lets you put in the specifications of the bearign that you need and it will show you which to buy. from what I can tell, you will need one exactly like what you took out with the exact measurments. http://www.thefind.com/sports/browse-42mm-metric-ball-bearings