Turbo SIM
（重定向自TurboSIM）
Turbo SIM card (also known as TurboSIM) is considered to be the forerunner of a large family of "Dual SIM" devices (HyperCard, HyperSIM, China3GPP, StealthSim, MagicSIMetc.) that piggyback on a mobile telephone SIM card to alter its normal operation. It was introduced on December 1, 2004 by BLADOX, located in Prague, Czech Republic. It is a very thin device with a 9mm by 9mm microprocessor mounted in the top right corner, with maker's name BLADOX in gold letters on its black PCB. It is pressed on top of a normal SIM card (with some plastic cut off) in such a way that it is still small enough to be inserted into the SIM card slot of any GSM phone. Without the TurboSIM, the original SIM card is usable as before.