Quality Park R5106 Quality Park Tyvek Heavyweight Jumbo Envelopes, 14-1/2x20, White,25/Bx Tyvek white large format envelope with an 18-lb. paper stock features a Flap-Stik self-adhesive closure. Lightweight. Use for negatives, art boards, blueprints. Wont abrade or chemically affect contents. Send or store large items.