Poweradd Pilot E2 12000mAh Dual USB External Battery Power Bank for $19.99

Poweradd Pilot E2 12000mAh USB Portable Charger External Battery Power Bank for $19.99.  Shipping is free on orders over $35.  If needed, use this Filler Tool to pad the order for free shipping.  Here is a screenshot for your reference.  It has dual output (2.1a + 1a) that allows charging two devices simultaneously, and relatively high power capacity of 12000mAh.