The balancer is used for checking the outer shell of a Torque Converters on the subject of uneven weight distribution. Just imagine an unbalanced Converter inside an Automatic Transmission and the harm it may do when rotating at high RPM values and you will understand its use. Transmission services implement these tools to avoid any disagreements with their Customers and ensure high-class remanufacture, though many rebuilders tend to rely on their expertise and produce quality results without them.