81 series filters are yellow-amber, and the kind of thing used for that Godfather movie look. Going from 81, 81A, 81B, 81C, etc, they get stronger. And unless you're trying to make a Sicilian mobster movie, anything stronger than 81A might look overdone. The European KR series is more pinkish-amber, a rather subtle distinction.
Just driving through our now dry inland agricultural valley with its veil of smoke and smog a couple days ago, everything had that Godfather movie glow on its own - no filter needed.