TS128GPSD320 128GB is an SSD type hard drive which can fit 128 GB of data. The form factor is 2.5" the most common for SSD drives.
From Amazon
128GB Transcend PSD330 2.5-inch IDE Internal SSD Solid State Disk (MLC Flash)
Memory C
128GB Transcend PSD330 2.5-inch IDE Internal SSD Solid State Disk (MLC Flash)
Conrad Electronic
Transcend PSD330 128 GB 2.5 (6.35 cm) internal IDE SSD IDE Industrial TS128GPSD330