I have used these envelopes to mail individual and corporate tax related documents to clients for several years now. They have never failed to deliver consistent quality. While I know the adhesive is strong enough by itself I cannot resist using a little tape to secure both ends of the flap.
This product fits our needs in an outstanding manner. We use them to ship new members materials. This includes I.D. cards Certificate information about the members responsibilities. The USPS do not have to stamp First Class on the envelope because it is already pre-printed on the envelope. The greatest benefit is the envelope withstands the punishment of going through the postal system.