Easy, simple to follow, simple to do, wide age-group. Great for the price.
Having used this trick for a while, I feel I need to update my review slightly. All is true, but in practice, it's definitely not a wide age-group. Great for kids, but many adults have quickly realized the outcomes. As such, getting a fairly good idea of the workings quickly. At least that's been my experience after more performances with adults. But, at the price point, it's good to have around for kiddies.