10K, or more specifically 10KmAh, refers to the portable charger’s rated capacity (mAh). This is the least output capacity under the rated voltage and current. For example, a power bank with a rated capacity of 10,000mAh would have a minimum output capacity of 10,000mAh. No matter what, the portable charger will provide 1,000mA of power to your devices per hour for 10 hours (or 2,000mA of power to your devices per hour for 5 hours), unless you are charging extremely high-powered devices, or are using the power bank in an extremely hot or cold environment. When searching for a new power bank, you want one with a higher rated capacity. The higher its rated capacity, the more power that your portable charger can supply to your smartphone, tablet, laptop, wireless earbuds, and other compatible devices before running out of juice. This will make your life easier than ever while you’re at work or on a long road trip, and give you greater peace of mind so you can focus on the important things in life.