These 10 x 13 inch First Class flat Tyvek® envelopes are built from 14 lb olefin, a non-woven polyethylene material that delivers substantially greater puncture, tear, and moisture resistance than standard paper envelopes. The self-seal closure strip requires no additional tape or adhesive, keeping outbound mailing workflows efficient.

The printed First Class border meets USPS First Class Mail appearance requirements, making these envelopes a practical choice for business correspondence, contract distribution, certificate mailings, and flat media fulfillment. Legal firms, healthcare administrators, financial institutions, and e-commerce operations commonly rely on this format for time-sensitive or appearance-critical outbound mail.

Constructed in a flat format sized to hold unfolded letter and legal documents, photos, and flexible flat stock without folding or rolling. Each case contains 100 envelopes and ships via parcel carrier.