Built for 24/7 surveillance AllFrame technology for better performance Designed to support up to 64 HD cameras Engineered for compatibility Compatible Devices PC Hard Disk Interface Serial ATA Brand Western Digital Series WD Purple 4TB Surveillance Hard Disk Drive – 5400 RPM Class SATA 6 Gb/s 64M Specific Uses For Product Business, personal Connectivity Technology SATA Hard Disk Form Factor 3.5 Inches Hard Disk Size 4 TB Form Factor 3.5 Inch