How to repair/replace iPhone 6s/6s Plus battery and display (Guides) - 9to5Mac
OEM Original Apple Battery for iPhone 6 6S 7 8 / 6+Plus 6S+Plus 7+Plus 8+Plus | eBay
Exchangeable Battery for iPhone 6S+/6+, iPhone 6S/6?
Apple Smart Battery Case for iPhone 6S review: Apple's answer to iPhone battery life: Slap a case on it - CNET
Exchangeable Battery for iPhone 6S+/6+, iPhone 6S/6?
Weight, size, and battery life: how iPhone 6s and iPhone 6s Plus compare to their predecessors
Exchangeable Battery for iPhone 6S+/6+, iPhone 6S/6?
Weight, size, and battery life: how iPhone 6s and iPhone 6s Plus compare to their predecessors
EMNT 4000 mAh Battery Compatible with iPhone 6s High Capacity A1633/A1688/A1700 Battery Replacement 【New Version】 with Repair Tool Kits and Instructions【2 Years Warranty】.
iPhone 6 & 6S battery replacement - YouTube
Amazon.com: Battery Case for iPhone 6s Plus/6 Plus/7 Plus/8 Plus 8500mAh, Rechargeable Charging Case for iPhone 6Plus Extended Battery Pack Charger Apple 6s Plus Portable Power Bank Cover for 7Plus 8Plus (5.5”) :
Exchangeable Battery for iPhone 6S+/6+, iPhone 6S/6?