Get the lasting durability of DuPont's Tyvek polymer with JAM Paper #7 Heavy Duty White Tyvek Coin Envelopes. These superior quality open-end envelopes are waterproof, stronger and more tear-resistant than regular paper envelopes. The straight flap provides a protective cover for your cards and the self-adhesive strip ensures they will be secure. Each 3.5" x 6.5" envelope in this 25 piece pack is perfect for mailing important documents at home, school, or work. They have a smooth finish and are manufactured from 10% recycled materials, making them stylish and eco-friendly. Tyvek is a registered trademark of DuPont, an established chemical company that develops the powerful polymer used to make these envelopes.Details:White3.5" x 6.5"WaterproofStraight flapSelf-adhesive strip25 envelopes10% recycled Tyvek polymer