Western Digital 6TB WD Purple Surveillance Internal Hard Drive HDD - SATA 3.5" | eBay
Amazon.com: Seagate 6 TB Enterprise Capacity HDD SATA 6Gb/s 128MB Cache 3.5 inches Internal Bare Drive (ST6000NM00) (Renewed) : Electronics
Western Digital Purple 6 TB,Internal,5400 RPM,3.5 inch (WD63PURZ) Hard Drive | eBay
Amazon.com: WD Purple 6TB Surveillance Hard Disk Drive - 5400 RPM Class SATA 6 Gb/s 64MB Cache 3.5 Inch - WD60PURX [Old Version] : Electronics
Amazon.com: Seagate SkyHawk 6TB Surveillance Internal Hard Drive HDD – 3.5 Inch SATA 6GB/s 256MB Cache for DVR NVR Security Camera System with Drive Health Management – Frustration Free Packaging (ST6000VX001) : Electronics