The 123ink packing list envelopes are transparent, so you can use them to stick a packing slip, invoice or other document to the outside of a package. This allows the recipient to immediately see what is in the package. The top layer is made of sturdy plastic, so that the document remains legible.
The envelopes read 'Documents Enclosed', so that the recipient knows that there is a document in the envelope.
Of course this 123ink product also comes with a 100% warranty!