HGST G-SPEED ES PRO 4000GB. Total storage capacity: 4000 GB, Hard drive rotational speed: 7200 RPM, Maximum capacity: 8 TB. Processor model: IOP348, Processor clock speed: 1200 MHz. Weight: 5.7 kg. Compatible operating systems: Mac OSX 10.3.x Windows Vista/XP/2000. Dimensions (WxDxH): 124 x 210 x 166 mm