Seagate SkyHawk 4TB Surveillance Hard Drive - SATA 6Gb/s 64MB Cache 3.5-Inch Internal Drive (ST4000VX007)
Avycon AVY-HDD-4TB Surveillance Grade Hard Drive 3.5 SATA 4 TB Capacity
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Amazon.com: WD Purple 4 TB Surveillance Hard Disk Drive, Intellipower 3.5 Inch SATA 6 Gb/s 64 MB Cache 5400 RPM : Electronics
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Surveillance Grade Hard Drive for your Surveillance System (1TB-20TB)
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