Ok so a better question is what is this for? Its a GE panel
On the 4th of July maybe:D
Sorry could not resist, no.
There’s always one in every group!
The thing is the circle is a stab to attach one-1" CB or two-1/2" CB’s on either side.
Thanks for the answer Robert!
You’re welcome. At first glance it appears that the screw is going through the bus into the cabinet but it’s only attaching the short stab to the bus. 