Tyvek (White spun bonded olefin)

Tyvek is a spun bonded olefin manufactured by DuPont. Their process produces an opaque sheet that is lightweight yet extremely strong. Tyvek resists water bursting and tearing. It is acid and sulfide free. The smooth bright white lint free surface enhances printed color type and graphics. These First Class envelopes come standard with a Kwik-Tak seal and are available as a flat or an expansion envelope.