I bought scotch tape for extra security I felt the envelopes won’t provide I was forced to buy because they didn’t have other peel n stick type envelopes in stock
These envelopes are hard to see through and fit my 8.5 x 11 printed invoices that I generate through quickbooks when I double fold them. It does the job.
I highly recommend this product. Preprogram the location of your destination and return addresses on your letter to match the envelope windows. Up to three sheets of paper are fine. They fit inside the envelope perfectly when neatly folded in third's. When using larger envelopes the letter may move and the address can slip out of the display window. I use these # 9 envelopes for all of my billings.