Heavyweight Tyvek Envelopes are super strong, moisture-resistant and tear-resistant. Tyvek expansion is ideal for superior protection for mailing bulky items. These plain envelopes feature an open-end design for easy insertion of documents. Convenient peel-to-seal closure requires no moisture to close. 12″ x 15.5″ – Peel and Seal – Tyvek – 50 / Box – White