poly string envelopes

Most use a button-and-string (two-button string-tie or string & button) closure—a simple reusable fastening designed to secure papers inside the envelope.

Most of the poly-style string envelopes are made from plastic materials such as polypropylene. Note that some listings in the set include paper coin/business envelopes, so material can vary—check the product description for each item.

Expansion varies by listing. Common gusset depths include 1 inch and 1.25 inches (1 1/4"), which accommodate bulkier materials and allow greater sheet capacity.

These envelopes are described as tear- and water-resistant, scratch-resistant, moisture-repellent, and easy to clean. Some listings also label them acid-free, PVC-free, or archival-quality to help protect documents.

Listings show top-load (top-opening) and vertical-orientation envelopes. Larger or legal-style options may use open-end or straight-flap openings. Check each product description for the exact opening orientation.