Amazon has EC Technology's popular 22,400mAh capacity battery pack available for just $19.79. It is priced at $32.99 over on Amazon, but with the promo code 2CLBJ2RY you'll get $13.20 taken off of the price, bringing it down to $19.79. That is a really good deal on a battery pack of this capacity. It's also worth noting that the price may not show until you go to checkout.
The EC Technology 22,400mAh Power Bank is a great battery pack to pick up. It has a capacity of around 22,400mAh, which is going to be enough to keep your smartphone charged up on busy days and while traveling. For most smartphones, it can charge it up around 8 times or more, depending on the size of the battery in the smartphone. On this power bank, there are three USB-A ports, all of which can do up to 2.4A. There is no Quick Charge functionality here, but you do get 2.4A output, which is going to be enough to keep your phone charged up and charge it up pretty quickly. For reference, 2.4A is about the same speed as Quick Charge 2.0. So you're still getting "fast charging" just not Qualcomm's official Quick Charge 2.0 or 3.0 here. This one is going to take a while to charge up, since it is a massive 22,400mAh capacity battery pack, but it will keep you going for a while.
This item is also eligible for Amazon Prime's free shipping. Which includes free two-day shipping, and pretty cheap (usually $3.99) next-day shipping if you need it extra fast. If you are not an Amazon Prime member yet, you can sign up for a free trial of Amazon Prime. You'll get 30 days free (if you're a student, you get 6 months), and then it's $119/year (or $59/year for students). Prime members do get a whole lot more than just free shipping though, so be sure to check out the full benefits.