Aukey is currently offering its 20000mAh power bank for just $21 with coupon code AUK2MAHL, a savings of $9 from its regular price. Along with featuring two USB outputs, the power bank itself can charge via either microUSB or Lightning, making it even easier to have it charged up all the time. For being such a large capacity, the battery pack itself is on the smaller side so you can carry it around with ease.
Don’t get caught without enough power to make it through the day, and instead be sure to pick one of these up. You may not find uses for it every day, but when you do you will quickly realize that it was $21 well spent.