Deliver priority forms in envelopes you can count on: Quality Park Recycled Open End Catalog Envelopes. Protected by durable paper and secured by strong latex closure – no moisture needed – just press for a secure seal – the contents will arrive safe and sound. As an added benefit, the brown, open-end Kraft construction is 100% recycled. Seam Type: Center; Flap Type: Cheese Blade; Trade Size: #10 1/2; Security Tinted: No.