Fern and Heather are correct, that's from my Aviary Cage Additions set.
It's available on my google drive with the current iteration of the set here - https://drive.google.com/file/d/13g1YThUKmPq9Gowf4RIwthkHknVmWyNf/view?usp=sharing
I don't remember exactly where I left off on the set, but usually if something made it onto my Drive folder it's finished enough to be playable. It's probably just that there was more I intended for the set that I didn't end up finishing, so I never submitted the set.
In the set there's also a 2H tall version of this fence and a few other files.
Good contender for another set to try and finish up this year to finally submit.
The post you quoted also reminded me of one benefit of having those concrete wall pieces as scenery and not just fences - scenery can be tankable, fences can't be. Good food for thought. I don't even remember writing that post, lol. The merciless forward march of time ...