uNu DX Plus Extended Battery Case for iPhone 4/4s DX-04-2400BS
External Battery Case For Apple Iphone 4/4S White Mophie Style | eBay
Apple IPHONE 4S EXTERNAL BATTERY CASE Cellular Battery BB-149401 - batterykings.com
Amazon.com: MFI-Apple Certified - ibattz Mojo Vogue Removable Battery Case for iPhone 4 and 4S White 1700mAhX2 fits all version of iPhone 4S/4 : Cell Phones & Accessories
Mophie Juice Pack Plus Protective Battery Case for iPhone 4/4S (Black) (Certified Refurbished) - Walmart.com