HeyBub wrote:

* Where do the house wires enter your box? If on the rear, you'll need a
hole saw because breaker boxes don't have knock-outs on the back. There will
be some jiggling to line up the hole with available acreage inside the box,
mounting hardware, and the entrance of the primaries.

My new one in the garage has knockouts in the rear. I forget the brand.
Still it was easier to drill my own hole to line things up nicely.