I have used Player Piano Company as a source of brass D-rings for
several years, usually discarding the accompanying but unwanted black,
gummed-fabric end tabs.
Now I wish I had saved those old end tabs, because the last order
I received no longer included gummed-fabric tabs like those that are
standard in the piano-roll industry. Instead the end tabs were
gum-less, peel-off-stick-on ones like the postage stamps now sold by
the U.S. Postal Service. They are made of a white plastic material
which you just peel off the backing paper and press onto your music
Whether they are better or handier than the old-style I can't say,
but they are what you get now.