Firstly, this is a product designed for the American market. Consequently no British coins fit in the gadget properly. You can just about get a 10p in with the use of some sticky stuff provided.
Secondly, once you have got your 10p in and tried out the trick you will have discovered it is utterly rubbish.
As the other review states, there is a second trick. This involves clipping a coin onto a thingy which is attached to a bit of elastic that goes up your sleeve. Apparently when you let go of the coin it shoots up your sleeve. Except it doesn't, it just dangles out of the end of your sleeve, looking a little bit sad.
You get what you pay for really, and you're paying for rubbish here.