A number of Top Trumps packs have Super Top Trump (STT) cards issued for them, also known as Supercards in the United States. These cards are not available with the original pack, but are found in related merchandise, events or promotions, and sometimes made available in booster packs of 2–10 cards. For example, the popular US television series 24 has a Top Trumps pack available, but its STT card is only available with the purchase of special-stickered season 4 of 24 DVDs. STT cards for the Doctor Who deck were only available with the purchase of season 2, 3 and 4 DVDs. One other Doctor Who Super Top Trump card was released with a very special edition of the "Beano" magazine. A number of STT cards were made available free of charge to members of the Top Trumps club through its website, prior to 2006.