Sunvalley Brands via Amazon offers the RAVPower 20,100mAh AC Outlet Portable Battery Pack for $79.99. Coupon code "USAPB21K" drops that to $74.99. With free shipping, that's the lowest price we could find by $5. It features a 65-watt 2-prong AC outlet, 3-amp USB Type-C charging port, 2.4-amp iSmart USB charging port, and on/off switch. Deal ends December 15.