This is not my first purchase. They are economical but don't keep closed sometimes. I always use a piece of tape to keep it closed when I mail something. The price is good.
These are defective. The positioning of the adhesive strip is too low and causes the adhesive to stick to the letter inside the envelope rather than adhering the flap to the back of the envelope itself. Plus it's not really strong enough so the part of the flap that isn't glued down catches on everything and lifts the whole thing up. Can't use them at all.