 "Western Digital Red 2 TB Internal HDD" " Western HDD - WD20EFRX Desktop Hard Drives CDWG.com
"WD's exclusive NASware technology, built into every WD Red hard drive, improves NAS storage performance by reducing common hard drive concerns in NAS systems including concerns for things like compatibility, integration, upgradeability, reliability and cost of ownership that are experienced with a hard drive designed for desktop computers." 
 "WD Blue 4TB 5400rpm SATA 6Gb/s 64MB Cache HDD (WD40EZRZ)"@en "▷ WD (WD40EZRZ) | OcUK"@en
"4TB Capacity, 3.5 inch, SATA 6Gb/s Interface, IntelliPower 5400rpm Spin Speed, 64MB Cache, 2 Year Warranty."@en 