Though there are dual-SIM card adapters available for iPhone 4, but they sure aren’t as classy as this dual-SIM case. We’re also hearing that iPhone 5 may actually offer dual-SIM by default. But those of you who can’t wait till the release of iPhone 5 for the dual-SIM functionality, can probably try this new iPhone 4 case called “Rebel 2Phone Dual SIM Standby Case” by Rebel SIMCard, which not only provides you with an extra SIM slot, but also offers you a secondary battery of 800mAH.