electrical knock out box holes

hello, in the electrical boxes/ knock out boxes there are lots of holes some larger than the others what are they all for? I googled but didnt come up with anything.
I don’t mean the ones that you take out to put wires through, I mean the small one on the sides other than the ground and attachment screws
virtually yours
Virtually Yours

Have you got a picture you can share? I’m not aware of any knockouts on an electrical box that would not be for wires.

Perhaps the heavy ground wire … 6 gauge I think … make sure you use a romex clamp to run the wires into the box …

hi, not talking about the knockouts, I am talking about the little screw sized holes all around it.
opps i think i found out what they are for, to attach a side bracket. saw it on this pic http://www.garvinindustries.com/electrical-junction-boxes/4-square-junction-boxes/1-1-4-and-1-1-2-deep/52151-3-4ab

here are a few other examples http://www.garvinindustries.com/electrical-junction-boxes/4-square-junction-boxes/1-1-4-and-1-1-2-deep

The little screw sized holes are for actual screws to mount the box to the wall.

You’ll find they are for fixings for the earth tags on steel wire armoured cable glands

Big ones for cable, little ones for multiple options for attaching the box with screws to something solid.