No office supply order is complete without the inclusion of #9 envelopes. These envelopes have the perfect size for sending few pages of A4 documents, receipts, and invoices. Their popularity lies in the fact that they are extremely economical and highly versatile. This particular #9 envelope comes with special security tint. The security tint creates an opaque barrier that completely blocks the view of the contents of the envelope from outside. These are the envelope of choice when sending checks or any document that contains sensitive information such as banking details. These envelopes are made from 24 lbs stock paper and they have a traditional moisture-sensitive seal. These envelopes are also typically used as business return envelopes.