What do you call the diagonal part of some barbed wire fences on the top? I am wondering if there's a particular word for it or not, because it's something common, but I don't recall it having a particular word. The best phrase I could come up with is "diagonal barbed extension."
You could describe that part as an "overhang", and some fence manufacturers do use that to sell such fences https://www.fenceall.com/product/barbed-wire-overhang/
Searching on the phrase
barbed wire fence angled part on top
gives some results, with lots of pictures. The links suggest the angled parts, which come in great variety, are sometimes called "arms".
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