Since it is not a catlogue, in that it does not offer to sell or contain prices and is not a magazine I believe it qualifies as media mail.

Media Mail Prices
The service for printed and recorded material.

For sending small and large packages consisting of books, film, manuscripts, sound recordings, video tapes, and computer readable media (such as CDs, DVDs, and diskettes).
Prices based on weight.

Just my thoughts.

Wishing all enough,
Dick Staefler R-3828