I Replaced My iPhone's Battery Myself and You Can Too - CNET
Battery for iPhone 6 Plus, Upgraded 4500mAh New 0 Cycle High Capacity Replacement Battery for iPhone 6 Plus Model A1522 A1524 A1593 with Complete Tool Kits: Amazon.co.uk: Electronics & Photo
Battery for iPhone 6S Plus, 4500mAh [Upgraded] High Capacity Li-ion Battery Replacement for iPhone 6S Plus, New 0 Cycle Battery for Models A1634 A1687 A1699 with Tools Kits (NOT for 6/6S/6Plus): Amazon.co.uk:
iPhone 6s Plus Battery Replacement - iFixit Repair Guide
Original Apple iPhone 6s Plus 2750 mAh Battery Replacement For iPhone with Tools | eBay