Quality Park Survivor R1460 Tyvek Mailer, 9 x 12, White (Box of 100) 9 x 12 inches 100ct. Tyvek Catalog Envelopes Tyvek is strong and moisture resistant. Convenient Flap-Stik closure requires no moisture to seal. Releasestrip makes document easily accessible to recipient, yet maintains security of contents 9 x 12 inches 100ct. Tyvek Catalog Envelopes