Blue Summit First-Class Tyvek Envelopes, 10 x 13 Redi-Seal Envelopes, White Tyvek with Center Seam and Green First-Class Markings, 100 EnvelopesPerfect for mailing catalogs, magazines, projects, or multiple documents at once. Professional and secure mailing envelopes constructed with durable Tyvek material that resists ripping, tearing, puncturing, and moisture. Easy to secure peel and seal closure has no need for licking or moistening and will stay sealed without tape or glue. Save time by quickly stuffing multiple pieces of business mail in the 10 wide envelope opening that supports