JAM Paper #10 business envelopes have wide straight flaps with dependable gum closures to keep items secure in transport. These envelopes are made out of 28lb, high quality paper. The size of these envelopes makes them perfect for three-time-folded standard sized sheets of paper. Use these envelopes for letters, documents, forms and more. Details:Smooth black4.125" x 9.5" (#10)28 lb. paperAvailable in multiple countsStraight flap envelopes