Universal Products - Universal - Pull & Seal Business Envelope, #10, Window, White, 500/Box - Sold As 1 Box - No moisture needed for these envelopes. - Simply peel back the strip and fold the flap closed. - Peel seal strip feature makes large mailings easier and less messy. No moisture needed for these envelopes. Simply peel back the strip and fold the flap closed. Peel seal strip feature makes large mailings easier and less messy.