Amazon.com: WD Purple 4 TB Surveillance Hard Disk Drive, Intellipower 3.5 Inch SATA 6 Gb/s 64 MB Cache 5400 RPM : Electronics
Wd Purple Surveillance 4tb Hard Drive Disk Sata Iii 64m 3.5" Hdd Hd Harddisk For Security System Video Recorder Dvr Nvr Cctv - Hard Disk Drive - AliExpress
Seagate Skyhawk 4tb Surveillance Hard 5900 Rpm Sata 6gb/s 64mb Cache 3.5-inch Internal Drive St4000vx007 - Hard Disk Drive - AliExpress
WD40PURX 4TB Surveillance Class Hard Drive from WD