Transcend 16GB (4GB x 4 Kit) JetMemory DDR3- 1333 ECC Registered DIMM 2Rx8 For Mac Pro Early 2009 (TS16GJMA533N) For Mac Pro Early 2009 256Mx8 bit 1.5V Timing 9-9-9 Operating Temperature 0 ~ 85 C Compatible with select Mac systems. Verify model for compatibility Registered DIMM 256Mx8 bit 1333 Mbps 1.5V Timing 9-9-9 2 Ranks Operating Temp. 0 DegreeC ~ 85 DegreeC Compatible with selected Mac systems. Verify model for compatibility