I paid extra for these envelopes because of the pull-off strip seal. I usually tape my envelopes closed (because I don't like to lick the glue or use the clasp) and I figured with these envelopes I would not need to use tape and it would save me a little time but I was wrong. I needed to mail about 100 monthly newsletters but by the time I labeled and stamped and sealed all the envelopes the seals were coming undone before I even got them to the post office. Therefore the seals did not stick. Someone at the post office had tucked the seals "inside" the envelopes but the sticky stuff stuck to my newsletters leaving the front page of my newsletters sticky. Therefore it was not worth paying extra for these envelopes. I guess I will buy cheaper envelopes and use tape as always before. Would like to see more sales on the 6" x 9" and 9" x 12" envelopes since I use over 100 per month.