Quality Park Open-end Envelope – Catalog – #13 1/2 [10″ X 13″] – 14 Lb – Peel & Seal – Tyvek – 50/box – White (R1582). Manufacturer Part Number R1582. Lightweight 14 lb Tyvek. Seam Type: Center; Flap Type: Square; Trade Size: 13 1/2; Security Tinted: No.