ATC LLC via Amazon offers the Lumsing 16,000mAh Portable Power Bank in Black, White, or Champagne for $25.99. Coupon code "92GYB3AT" drops it to $15.99. Plus, Prime members bag free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.55.) That's $64 off and the best price we could find. It's compatible with most smartphones, tablets, and other USB devices. Deal ends April 18.