Envelope Sigel DU443 DIN lang (no window) – Sigel DU443, DIN lang format

Sigel DU443 DIN lang envelopes without window are standard-sized postal envelopes designed for mailing letters, cards and invoices. The plain front surface provides space for address labels or decorative elements, while the absence of a transparent window ensures privacy and a consistent appearance. These envelopes suit both personal and business correspondence and are compatible with standard DIN lang documents and mailing equipment.

Advantages

These Sigel DU443 envelopes combine a uniform DIN lang format with a smooth, unwindowed front that simplifies printing or manual addressing. The construction supports easy insertion and reliable sealing, and the plain face allows use of stamps, printed labels or handwritten addresses without the alignment constraints of windowed envelopes. They are produced to standard dimensions for compatibility with mail-sorting systems and common office workflows.

Suitable for

• Mailing business letters, invoices and reminders
• Sending greeting cards and invitations
• Organizing internal office paperwork and correspondence
• Use with address labels, stamps or printed fronts

Key specifications

• Format: DIN lang (standard long envelope size)
• Front design: plain, no transparent window
• Material: paper suitable for mailing and printing
• Closure: adhesive sealing flap
• Compatibility: fits DIN lang documents and standard mail processing equipment

How to use

Insert the document or card flat into the envelope so that the address area on the front remains clear for labeling or stamping. If printing addresses or using labels, ensure alignment with the plain front surface before applying. Close the envelope using the adhesive flap and press firmly to secure the seal. For high-volume use, verify compatibility with your inserter or mailing machine by testing a single envelope first.

Usage recommendations

Store envelopes in a dry, flat place to prevent bending or moisture damage. When printing directly on the envelope, use settings appropriate for paper weight and perform a test print to confirm correct feed and alignment. For confidential documents, choose the unwindowed front to prevent visibility of contents and consider additional sealing methods if extra security is required.