Monadnock Clip Nut
Exactly what I needed and delivered before I expected it.
I find the Monadnock is less high where the spring clip bends back on itself relative to the similar Tinnerman. Unless you have thick metal that you are sliding the clip nut over, the Monadnock might squeeze tighter. Each brand has their purpose. With the Tinnerman, the threaded insert is perhaps better anchored, but I have not had any problems with the Monadnock style.
This has a .83" length x .415" width x .263" height (from bottom of the clip to the top of the nut).