Use this ProSeries compatible envelope with your ProSeries generated slip-sheet. This First Class Mail portrait envelope with double windows is designed specifically for your ProSeries software. It is 9.5” by 11.5” and is available in a self seal version ProSeriesPEU21. This envelope is also compatible with the ProSeries folders see items ProSeriesSFGR14, ProSeriesSFDB04, ProSeriesSFG24 and ProSeriesSFR34.