I can use this power bank to charge up to two devices at once. And at 15000 mAh, I can charge them over and over and over. You know they mean 15000 when you feel the weight. Just look at that thickness. For anyone who doesn’t understand what I’m saying, a power bank with this much juice should feel heavy and have good size. If it’s small, lightweight, and thin, you’re not getting what you’re paying for.