The "HDL2-AA Series" is a 2-drive model network HDD (NAS) with dual core CPUs for read up to 116 MB/s and ultra-fast data transfer. Adopts IOs proprietary data protection technology "Extended Volume" used in NAS for businesses, similar to the traditional RAID 1 (mirroring) to protect important data during a single hard disk, but also reduce the risk of two hard disks at the same time. We also increased convenience and redundancy for expanding capacity while storing data. In addition, it has a wide variety of functions that can be added to the necessary functions and data copy function that can easily migrate data, which tends to be troubled when buying from an old NAS.