For iPOD / MP3 / PMP Battery Fit For iPOD 4th Generation battery (1200 mAh) new - AliExpress Consumer Electronics
Amazon.com: i-Blason Battery Case Designed for iPod Touch 7/6/5, 2200mAh Portable Charging Rechargeable Extended Battery Slider Case for iPod Touch 5th/6th/7th Generation, Black : Electronics
How to: Replace iPod Touch 4th Gen Battery | DirectFix - YouTube