I bought this case for a MyBook External HD KINGSTON FLASH MEMORA that I bought. The HD fits snugly in and the main pocket has a velcro panel to adjust the size. There is a zippered pocket in the lid for cords and the remaining space in the main pocket is great for the power pack and cord! All in all this case is perfect for MyBook External HD's and I'm sure that other medium sized HD's would also fit perfectly!