I really like these envelopes for mass mailings. The easy pull strips replace the foul taste licking envelope glue. And these evelopes seal great! The one flaw I've found is the need to open bottom corners to slide in cards they are sometimes glued but can be easily opened without damaging the envelope. I ususally find 3-5 such envelopes in each box of 100. So no real problems and great ease of use!