 "WD Purple WD10PURX 1TB Surveillance 3.5" Internal SATA Hard Drive"
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                Overview:
The 1TB Purple Surveillance Internal Hard Drive from Western Digital is designed to withstand the stresses placed on it in a 24/7 surveillance system. With support for up to 32 high-definition surveillance cameras this 1TB hard drive can hold a large amount of data and gives you the ability to easily upgrade and expand your security system.

Built for always-on surveillance storage applications
AllFrame technology for reduced pixilation and video interruption
Designed to support up to 32 HD cameras
Caching algorithms specifically designed for security surveillance operation
1 TB capacity holds up to 200,000 digital photos, 250,000 MP3 files, and 120 hours of HD video.

Specifications:

1TB Storage Capacity
3.5 Form Factor
6 Gb/s Data Transfer Rate
64MB Cache
Surveillance Class Storage
Supports up to 32HD Surveillance Cameras

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 "WD Blue WD5000AZLX - hard drive 500 GB SATA 6Gb/s" " WD 6Gb/s Internal Desktop Hard Drives CDWG.com
"Built to WD's highest standards of quality and reliability, WD Blue offers the features and entry-level capacities that are ideal for your computing needs. WD Blue is designed by the brand that you trust with the quality you would expect for a tested, proven, everyday storage solution.WD Blue storage is designed and manufactured with technology found in WD's original award-winning desktop and mobile hard drives. WD Blue sets the baseline for everyday storage by consistently delivering improved performance over previous generations while successfully maintaining WD's quality and reliability for over six generations. The difference is that their colors never fade, generation after generation.WD Blue is available in a broad range of entry-level capacities, cache sizes, form factors and interfaces so you can be sure there's a drive that's the perfect fit for your system. However, not all hard drives are created equally and for your applications that demand more, WD gives you the power of choice." 