If you already purchased one USB SIM card manager and you want to create more Multi SIM clones - then this product is just for you.
Multi SIM technology is an amazing thing. You can clone up to 12 GSM SIM cards (of format COMP128v1) into one Multi SIM card. After that you can leave your original SIM cards in some secure place at home and use only the Multi SIM card in your day to day life.
Multi SIM card allows switching between (up to) 12 stored numbers right from your phone's main menu (a new menu entry in your phone will automatically appear after you insert the Multi SIM card into your phone). You don't need anymore to extract the phone's battery or even to turn off and on the phone in case to change the number!
At a time only one of the cloned phone numbers may be active, all other cloned phone numbers will be unavailable as if they were turned off.

The Multi SIM technology is for several years here now and is a result of a poor security algorithms used in the encryption of the first generation of GSM SIM cards, what is also commonly called COMP128v1. Since then, the SIM cloning is now more difficult to perform, as more and more mobile operators are moving towards newer generations of encryption methods used in GSM SIM cards (like COMP128v2 or COMP128v3). But SIM cloning is still possible in with some operators in some countries like Russia, Iran, China and so on. SIM cards issued before June 2002 most likely are COMP128v1 SIM cards, thus clonnable.
Multi SIM technology of programming information from several SIM cards into one multi functional SIM card has nothing to do with the Multisim™, which is a respective property and trademark of National Instruments.