Western Digital WD5000AAKS Caviar Blue 500GB 3.5" 7200 RPM 16MB Cache SATA2 3.0 Gb/s HDD Hard Disk Drive WD5000AAKS-402AA0.Model Number: WD5000AAKSWD Part Number: WD5000AAKS-402AA0Apple Part Number: 655-1566CCompatible Part Numbers: 771640Specifications:Form Factor: 3.5"Interface: SATA2 3.0 Gb/sCapacity: 500GBCache: 16MBRPM: 7200 RPM