Home depot has something similar, but without the hole. I had to
replace one on a sliding glass door once, but I don't remember what
they are called. They are made of thin aluminum and probably aren't
strong enough foir furnature if there's a pulling stress and not just a
sheer.. This type is simply kept from turning by being pressed against
the surface when the screw starts to get tight. If you look carefully
at the ones you're tlaking about, I bet you'll find that the hole has
flat surfaces on the inside and takes an allen wrench. I think I've
seen them on furnature before, but I've never seen them sold
seperately...