There is a bolt that holds the standoff to the metal cap. The standoff has a flange and is predrilled and tapped for two 4-40 screws which hold the box to the flange. I even drilled a hole in the side of the battery box so I can loosen the bolt that secures the standoff to the cap so it makes it easy to remove the battery box from the cap.

If the pumps goes in a year I'll buy a better pump, no big deal.