SINGLE BULK PACK WD Green 1.5 TB SATA 3 Gb/s 2.5-inch Internal Mobile Hard Drive. WD Green (WD15NPVT) 2.5-inch hard drives are designed for use in custom-built external enclosures and other applications for which low noise and low heat are beneficial.* These earth-friendly hard drives are ideal for use whenever energy efficiency is needed. *Cannot be used in laptop or notebook computers. Designed for PCs and custom external enclosures. Consult system specifications for maximum allowable drive height before attempting to install. 8MB Cache, IntelliPower RPM