There are 12 products.
A glass full of milk is emptied in to another glass, yet the first glass is still full.
Pick up a piece of wire and apply some heat. As the wire heats up it twists and turns until if forms the shape of a selected card. Everything can be examined before and after.
Master the ultimate card trick! Introduce a wild card and use it to change the value of all the other cards even after you have showed them to be different.