This is the world’s thinnest ever iPhone case with battery charger that nearly doubles the life of your battery. Say goodbye to chunky and clumpy additions to your iPhone that can make it almost impossible for it to fit in your back pocket. With the Power Skin’s sleek and form fitting design we are extremely confident you will love this product. MiLi Power skin comes in a variation of colors, so we guarantee there will be something that fits your style. The Mili Power Skin gives you up to a whopping 19 hours audio play time, 5.4 hours of video playing time and up to 230 hours of stand by time, never again will a commute into work be boring! Not only does this battery pack give you unrivaled power reserves but it also protects your treasured iPhone from knocks and scratches with its hard shell case. The MiLi will accompany you and your iPhone through great and wonderful times -- you can enjoy your movies, music, phone call and internet surfing. You will never worry about shortage of battery power when enjoying the iPhone's colorful features. MiLi Power Skin is compatible with iphone 3G1.1, 3G2.1, 3GS. You can use the included USB cable to charge the MiLi Power Skin. When the iPhone is securely placed in the MiLi and connected to an electrical power source, the iPhone will be firstly charged until full, then the Power Skin next. Press the power button to start charging in condition of no external electrical source connected. MiLi Power Skin will stop charging automatically when iPhone is fully charged. Press the power button or connect with electrical source if recharge in need. Remarks: Please use apple original charger, PC or MiLi charger to charge MiLi Power Skin. When using the MiLi Power Skin with your iPhone, you can sync your iPhone with iTunes without removing the MiLi Power Skin.