Cardboard Envelope A3 352×520 mm Brown — Protective mailing envelope, model EB177180857

Rigid cardboard mailing envelope sized for A3 documents (352 × 520 mm). The brown protective envelope model EB177180857 is designed to ship or store flat items such as documents, posters, certificates or thin prints. It provides firm support to prevent bending during handling and transit and is suitable for mailing, archival storage, or office use.

Advantages

The envelope is constructed from rigid single- or double-wall cardboard that maintains flatness and resists crushing. Its precise A3-compatible dimensions (352 × 520 mm) ensure a snug fit for flat media without excessive movement. The brown kraft surface offers a neutral, professional appearance while providing a degree of moisture resistance compared with standard paper sleeves. The envelope is lightweight for economical shipping yet stiff enough to reduce the need for additional protective inserts.

Suitable for

• Shipping A3 documents, posters and certificates
• Archival storage of flat prints and drawings
• Transporting thin framed or unframed prints and photographs
• Office filing and inter-department mail for large sheets

Key specifications

• Inner dimensions: 352 × 520 mm (sized for A3 media)
• Material: rigid brown cardboard (kraft finish)
• Closure type: flap closure suitable for adhesive or tape sealing
• Stiffness: crush-resistant construction to reduce bending
• Appearance: brown, neutral surface for labeling and postage
• Use: single-sheet or small multi-sheet flat items (documents, posters, prints)

How to use

Insert the A3 document or flat item so it lies flat against the interior surface, ensuring edges are aligned with the envelope opening. Fold the flap over and secure with an appropriate adhesive, tape, or shipping label seal to prevent accidental opening. For additional protection, place a thin protective sheet such as tissue paper or a cardboard stiffener inside before inserting the item. Label the exterior with recipient and return address information and apply postage as required for shipment.

Usage recommendations

For valuable or fragile prints, combine this rigid cardboard envelope with a corner protector or additional stiff backing to minimize edge and corner damage. When mailing internationally or through automated sortation, reinforce the closure with tamper-evident tape and use a clear address window or securely affixed label for machine readability.