catalog mailing envelopes are perfect for shipping, storing, organizing white wove stock withstands extensive handling at Home, in the Office or on the Mail route and provides a clean, professional look. envelopes (6 x 9) are perfect for small flat or larger folded documents. 6 x 9 catalog mailing envelopes are ideal for small, heavy inserts or greeting card. bright white wove envelopes with strong center seams Sturdy envelopes are opaque and ideal for privacy and durability Heavily gummed envelopes provide a secure seal to keep contents contained. center seam holds up to heavy weights and wear and tear Opaque kraft paper stock prevents viewing of contents.