He uses a combination of tools. First it does involve magnetics.... the magnet is powered with abattery and worn around wrist, the card has an opposing magnet inside the card, it is an educated guess that most women will pick the queen of hearts or diamond or king of heats or diamond. These are placed in certain spots when he starts and he guesses. it is a one in four chance he guesses the right one- they don't show the failures. the last part of the trick uses a reel which runs down the arm and around the wrist and to the pre-selected card. that is my best guess.... sorry if it is not completely correct but I bet it comes pretty close.