Surge Suppressor?

I know that similar questions have been asked before, but is this round gray plastic device that’s attached to the side of the service panel, a surge suppressor? It was double tapped at the entrance cable terminals.




I do believe they should be mounted outside the box (as your pic shows) instead of inside the box as shown in the link.

They should be connected to a load side breaker, not the service conductors.

Thanks for the info, Greg and Todd!