Regarding Ed Gaida's comment on this subject, as well as reading some
bogus 'sales statements' concerning shipping rolls on eBay via anything
else other that Priority mail, prompts me to add this comment to the
mix.

There _is_ something one can do in addition to merely marking it
"Media Mail".  I have had great success by adding the phrase

  Contents: Piano Roll Sound Recording, USPS Regulation 273.3.3e

as a sub-label to the package.  It helps if you print a professional
looking page of lines regarding this instead of just penciling the
statement under the address lines.  The Postal Code Domestic Mail
Manual (273.3.3e) itself clearly states the term: "Sound Recording"
and reflects paper piano rolls as a "sound recording".

Yes, the package is still subject to opening, and yes, even in the
last 20 years there were few [post office workers] who actually knew
what a piano roll was.  Still, there is still a _lot_ less tampering
now if one 'appears official' and directs the reluctant inspector
to an official page of their own manual.

As in everything else, if one even "appears" to be professional in
labeling or merely "sounds" educated in the Postal System code, they
will often let it pass without opening it.

The Postal Service actually dislikes people to use this more economical
method as they do not make as much money, but the fact is also that
there have many, many people to abuse this class of shipping to the
point that USPS had to do something because people were shipping all
kinds of things disguised as "media".  We need not just back away and
abandon this one break that we in the mechanical music trade have ever
gotten from the Post Office, or we will lose it for sure.

Insure the package if you must, but proper marking goes a long way to
lessen their tampering with your package.

Dave Haibach - Enjoying the off and on again winter time in Kentucky.