It should be compatible with almost all HDD and SSD devices that support USB 3.0 option. We have tested it with a 4TB external drive.
We recommend that the PowerHub be plugged in to a power source first after which you connect the HDD or SSD since HDD and SSD devices tend to draw a lot of power initially.
5000 mAh - which is better than most products in this category. We tried to stuff in more power but found that the PowerHub was getting heavier. 5000 mAh was the perfect balance between substance and style.