Mounting brackets

Can anyone tell me what hooks / mounts use these holes ?

 

IDing the bedcover might help find your answer.

 

It’s a retrax. But the previous owner screwed the track to it.

 

I'm still confused. What holes?

If your asking what mount rack can use the track that is screwed to your retrax, your guess is as good as ours but I doubt any vendor is going to stick their neck out and say that their rack will function on an unknown track. If you are wanting to really use a rack over the retrax, you can but the side pieces from Retrax that come with the built in rails and then you can easily find compatible racks that will fit and function as expected.

I'm not saying what you have won't work, but its an unknown that won't be covered by any warranty out there.