Vantrue via Amazon offers the Solove Titan Ultra Slim 20,000mAh Dual USB Portable Charger / Power Bank in Dark Grey, model no. A8, for $46.99. Coupon code "FFSZPXZX" cuts it to $34.99. With free shipping, that's $95 off list and the lowest price we could find. It features over-current and over-heating protection, can charge two 5-volt devices simultaneously, and includes a digital LCD indicator.