Neenah Astroparche Fine Business Stationery Envelope, 4.125 X 9.5 Inches, Blue, 50 Count (26145) Acid and lingin free for great quality that doesn't deteriorate Inkjet, laser, copier and offset guaranteed Envelopes to ensure that everything you mail makes a great impression The paper is made with 30 percent recycled post-consumer fiber 50 Envelopes