I mail mine from the town I work in...NOT the town I live in because they always always are cheaper than the "bigger" place I live. It was a tight fit to get all 15 in the cardboard but they fit and they sold me a stamped, undated envelope that I put in there also so either way I think is great! Might have to go to the legal size sending the completed blocks back though and I think they will be thicker than the F8's?