The CP 010.04 Rigid All Board Envelope is a strong and reliable option for sending flat items that need firm, bend‑resistant protection. Made from durable E‑flute corrugated cardboard, it provides the rigidity needed to keep contents flat and secure throughout the postal journey. With external measurements of 245 x 350 mm, this envelope includes pre‑creased folds that allow the depth to be adjusted up to 50 mm. This makes it easy to tailor the fit to the contents, helping to reduce movement and improve protection during handling and delivery. It’s well‑suited for books, catalogues, calendars, artwork, prints, documents and other items that shouldn’t be rolled or folded. The maximum internal size of 235 x 340 x <50 mm* offers practical space while keeping everything neatly in place. Packing is quick and tidy thanks to the peel‑and‑seal closure, and customers benefit from a clean, simple opening experience with the integrated tear strip. *Effective internal size reduces as content thickness increases. If you're looking for something with a little more depth variability, check out CP 010.84 with a max depth up to 72mm.