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.