SanDisk External Battery Pack for iPhone 6/6s - Retail Packaging - Grey Works with iXpand Memory Case for iPhone 6 or iPhone 6s Delivers extra battery life, pre-charged and ready to use High quality: 1900mAH lithium ion polymer cell, rechargeable for full 500 cycles Intelligent smart charging circuitry for a quick charge, app detects low phone battery and automatically begins charging You are in charge - you determine when to charge your battery, or let our app do it for you with predetermined charge levels so you don't have to remember to turn the battery on