Print File NP57 Unbuffered Negative / Print Envelope 5-3/8x7-3/8" - Package of 100 Acid-free and lignin-free 7 pt. cardstock protection for prints and negatives Use envelopes with FoldFlap polyester sleeves for added protection and handling Envelopes are sized for corresponding FlipTop Boxes Neutral Ph adhesive used on the balance, side-seam design Thumb-cut on opening allows convenient access