Western Digital Purple 4TB 3.5" SATA III (models:WD42PURZ/WD43PURZ)is a specialized internal hard drive with twice the capacity of the previous model, intended for continuous video surveillance 24/7.

• Capacity: 4 TB (about 3725 GB real available space)
• Size (Format): 3.5 inches
• Interface: SATA III (6 Gb/s)
• Rotation speed: 5400 RPM (for quieter operation, less heating and lower consumption)
• Cache memory: 64 MB or 256 MB (depending on the subvariant)
• Transfer speed: Up to 175 MB/s or 180 MB/s