Narwhal tusks (pre 1972) can be shipped within the U.S. and with an export permit can be shipped to some countries overseas.  The average size is 6’-7’ but can be much longer, these came into the U.S. from Canada before 1972 (45 years ago).   When the Marine Mammal Protection Act was enacted it ended the importation into the U.S. but grandfathered/allowed the trade in tusks already here.  We acquire these from individuals and estates, they are rare and pricey we usually have at least one, please inquire.