I imagine the person installing the gate will know.

Ask the mason.

For the post the gate is attached to?

You won’t hang the gate on that. I’m guessing there will be another type hook that screws onto this that’ll look like an L or J that your gates brackets will fit over. DH’s cattle gates work similarly except his hook is all one piece and it screws inside the wooden gate posts. Since yours is into concrete, it‘s probably configured differently than his but will work the same. Your mason or gate installer will know for sure. (Sorry if my terminology isn’t precise....thingamajig didn’t seem appropriate but that’s what I’d have called it 🤣)

Perhaps those are bolts to secure a 2x4 to the masonry that the hinges would be screwed to? What do I win?

You win a Lysol inhaler, Mark :)

Bischak for the win.

I can keep it in my first aid kit next to my Clorox chewables.

@shead I know the ones you're talking about. Too bad he didn't put those in.

I no longer have the masons contact info, it's been years (its one of those projects)

I think I'll have to go with @Mark Bischak, Architect and attach a 2x4 to these bolts. Thanks all for the help!

maybe a transitional like so...

https://www.truevalue.com/aluminum-gate-ell-with-nuts-bolts-1-3-8-x1-3-8-i

@badabing2 ooh, that might work! thanks for the link!

He should have used a hinge bolt

Have the gate people (if you cant do it yourself) cut that bolt off and install something like this

I like the bolt as it is. It allows you to fasten a wood jamb and that allows nicer and more accurate hinges.