Entendo se tratar de uma tarifa para frete de materiais impressos, como revistas, folhetos etc.

Fontes de apoio:
"The first concessionary rate for printed materials was the 'Book Post', introduced in 1848 at the suggestion of Rowland Hill, with the aim of encouraging the circulating libraries of the time. From at least 1852 the regulations were extended such that practically any printed matter could be sent, provided that letters were not enclosed and that the packets were open to allow inspection."
http://www.gbps.org.uk/information/rates/inland/printed-matt...

"Printed matter was produced by printers or publishers, such as books, magazines, booklets, brochures and other publicity materials and in some cases, newspapers. Because much of this material is mailed, it is also a category of mail, accepted for delivery by a postal administration, that is not considered to be first-class mail and therefore qualifies for a special reduced printed matter postal rate."
https://en.wikipedia.org/wiki/Printed_matter

"Muitas formas de promoção estão disponíveis como sites de busca e banners em outras páginas da internet e, nesta era digital, são comuns empresas ignorem outras formas de divulgação, não menos eficazes, como os impressos promocionais."
https://www.printi.com.br/blog/5-pontos-de-atencao-para-cria...