Ordered the stuff about a month ago and just got around to opening it last night as we prepare for a trip next weekend. I have to say, this was a lot of fun to do together with a group of friends, and it actually will be very useful. It was also fun and difficult not to try to create some not so politically correct signs along the way. As much as we enjoyed ourselves, I have to say this is a serious educational opportunity that makes you realize just how few signals most divers use to communicate while underwater. We plan on taking it on our trip with us in an attempt to get others to learn it between dives while on the boat. I do see a lot of potential for this product. I only wish I could teach it as a PADI divemaster.