These envelopes are good for our purpose but as a non profit organization we find the cost to be high. We do not need to conceal contents but we do need the envelope to be durable enough to survive mailing to foreign countries which takes up to 3-4 weeks intransit. These envelopes seem to provide that durability and generally are fairly easy to seal and stay sealed. The construction is usually satisfactory surviving going through my printer to print addresses and sometimes surviving the round trip for six months to a year when the "to" address is wrong insufficient or the intended recipient has moved.
we use a lot of envelopes for routine things and do not need security. These envelopes cost less than half what similar envelopes cost that have security linings or are self-sealing neither of which were qualities we needed. Among its advantages is the standard postage required since it is a #10 and goes for the lowest first class envelope rate. It is hard to wax rapturous over an envelope that is standard and familiar to everyone utilitarian and in no way exceptional - except for its price which provides a good value for those who just need an envelope nothing fancy or elegant.