Premier 11B Envelopes are made using heavy grade 80 GSM paper which is FSC certified, making them an environmentally friendly choice. You can use laser or inkjet printer to effortlessly print on the envelopes. You don?t need any extra glue or tape to seal theses envelopes as it features convenient peal and seal closure. They have a security lined print inside the envelope which protects your secretive information from being read.