SupremeX Outside Side Seam High Efficiency Envelopes - #10 - Reverse Flap - Window - 4-1/8" x 9-1/2" - 500 packThis envelope is made with wider and outside side seams which help prevent jamming when sheets are inserted. It features security Artline, which provides added privacy for the contents inside making it a great option for sending utility bills, credit card statements and more. It also has a reverse flap on the bottom edge of the envelope and a clear poly window for easy view of addresses.