Use 2 SIM cards in 1 iPhone - just one click to switch between the cards! This ingenious case allows iPhone 4/4S users to have 2 SIMs installed at the same time, making it the ideal tool for travelling or business. The case requires NO software installation, no tool for switching between the two SIM cards and there is no need to jailbreak your phone! It accepts both standard SIM and Micro SIM cards. Simply activate the switch on the outer case to change the SIM in use.