I've always liked this effect a lot. I first bought, many years ago, a version made from Bicycle cards. I don't know who invented it, but the Tenyo version uses the exact same method.
Tenyo's version seems to be less reliable - the glue wore off very quickly and the gimmick doesn't 'stick' so good ... .
Nice trick, but I'd buy the Bicycle version which looks less suspicious because, well, it's made out of Bicycle stock. And, at least in my case, it works better.
Thanks for creating this thread JohnM and thanks for the review David I will probably get 1 of this but only to collect it but will never open it. I still love the Bicycle version too as David mentioned