What is the Blue Item in the Big Boy Disconnect Relay?

Question: I purchased one of your 00-00507-512 Battery Disconnects.

In the box was the relay as well as a small round blue item.  It has no labels so I’m not sure what it is.

Answer: A varistor assembly or surge suppression part can be used with the Big Boy relay and is included in the packaging. It is intended to suppress any back EMF that sometimes occurs when the contact is opened under load.

For more information, check the Big Boy Varistor Installation Notes.