These are basic envelopes for frequent use sold at a good price even when only buying small amounts. The white ones have been printed with grey colour on the inside of the mailer with an eye to keeping the contents away from prying eyes. The brown version, of course, does not need this addition because you cannot see through them anyway.

Here are the respective grammatures:

• C5 format: brown natron paper ca. 90 g/m² or, alternatively, white offset paper ca. 90 g/m²
• C4 format: brown natron paper ca. 90 g/m² or alternatively, white offset paper ca. 90 g/m²
• B4 format: brown natron paper ca. 110 g/m² alternatively, white offset paper ca. 120 g/m²