WD Redâ„¢ Plus NAS Hard Drive 3.5" 4TB WD40EFZX Features: For Small or Medium Businesses Exclusive NASware 3.0 Built for Optimum NAS Compatibility WD Redâ„¢ Pro for Big Business 3D Active Balance Plus 24/7 Environment Premium Support and a 3-year Limited Warranty Specifications: Capacity 4 TB Cache Size 128 MB Disk Speed (RPM) 5400rpm Interface SATA Transfer Rate up to 175MB/s Compatibility Designed with CMR technology for small or medium-sized businesses in RAID-optimized NAS systems with up to 8 bays. Perfect for handling increased workloads, including expanded OS compatibility and ZFS. Recording Technology CMR Dimensions (L x W x H) 146.99mm x 101.6mm x 26.11mm