DX4-TB2 supports 4 pieces of 2.5" HDD/SSD.  You could set 4 of them with RAID X mode which still protects your data from two defective disks at the same time.  It's just like what RAID 1 mode can do for you and even with a better data protection feature than that of RAID 0 mode.  And also, you could get the same data transfer rate as what RAID 0 provide you.  DX4-TB2 not only provides you an excellent data protection but also a good data transfer performance.

1. Thunderbolt 2.0 brings you an extreme high data transfer speed.

2. Transmission performance than the USB 3.1 to be about 2 times faster.

3. Raid X features provide the data protection and can be meantime error tolerance for each 1 HDD on RAID 1. 

4. Its Background REBUILDING feature lets you keep a stable data transfer efficient even though it's at REBUILDING WORKS.

5. Double Tray Lock designs helps reducing the DEGRADED RAID happening from extracting HDD/SSD Trays accidently! 

DX4-TB2 supports Thunderbolt 2.0 (TB2) interface for an extreme high data transfer speed.  And both of the two TB2 ports are equipped with up to 20Gb/s data transfer rate which is 4 times faster than USB3.0 ,2 times faster than USB3.1 and even 3+ times than SATA III interface.  You could definitely use it to play your 4K high-resolution films with no any lagging hassle.  Thunderbolt 2.0 interface not only brings you this high data transfer rate advantage, it also let you chain maximum up to 6 products (or other compatible storage products).