From Bro Gilbert: There was a slight change in the type of Envylope paper used in the current run... due to availability of the specific paper stock at the time. There is very little practical difference between the two paper's. Both are non-tearable. Both look like normal envelope paper. Both will last a very long time. Only real difference is the current paper is a bit stiffer. So the secret flap has to be broken in by hinging it back and forth 20-30 times to remove all the springiness. Other than that...both paper stocks works equally as well for the Envylope change.