WD Scorpio 2.5-inch drives offer high-performance, low power consumption and cool operation, making them ideal for notebooks and other portable devices. 
 
Specifications

Model Specifications
Internal / External Internal
Form Factor Width 2.5in
 
Performance Specifications
Buffer Size 8 MB
Average Seek Read 12.0 ms
Average Latency 4.20 ms
Average Seek Time 2.0 ms
Interface transferring rates 3 Gb/s
 
Physical Specifications
Formatted Capacity 320 GB
Rotational Speed 5,400 RPM
 
Interfaces/Controllers
SATA SATA 3 Gb/s
 
Dimensions
Width 2.75 ±0.010 inch
Height 0.374 ±0.008 inch
Depth 3.94 ±0.010 inch
Weight 0.26 Pounds