ATC LLC via Amazon offers Prime members the Lumsing 10,400mAh External Battery Pack in White, Black, or Gold, model no. LUM-008-01, for $19.99 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, it costs $5.25.) That's tied with our May mention, $40 off, and the lowest total price we could find. (It's also $4 under the best price we could find for a comparable 10,400mAh pack elsewhere.) It is compatible with a range of Apple and Android devices and features four LED indicator lights and micro USB input.