Manufacturer's Part Number: WD40EZRZ 4TB of capacity 5400 RPM is the rotational speed. 64 MB is the class cache. SATA interface 6 Gb/s Maximum Data Transfer Rate: 6 Gb/s is the buffer to host. 150 MB/s for host to/from drive (sustained) Startled: Running: 65G @ 2ms (read); 30G @ 2ms (write) Not in use: 250G @ 2ms Sound: 25 dBA is the idle mode. Average Seek Mode: 28 dBA Power Management: 1.75 A at 12VDC ± 10% (peak) 5.3 Watts to read and write 3.4 watts at idle Sleep and Standby: 0.4 Watts Dimensions: 3.5 inches Measurements (WxLxH): 101.6 x 147.0 x 26.1 mm / 4.000 x 5.787 x 1.028 inches Weight: 0.68 kg/1.50 lbs Compliant with RoHS