OWC 64.0GB (4 x 16GB) PC3-14900 1866MHz DDR3 ECC-R SDRAM Memory Upgrade Kit for Mac Pro 2013, ECC Registered, (OWC1866D3R9M64) 64.0GB Mac Pro Late 2013 Memory Matched Set (4 x 16GB) PC3-14900 1866MHz DDR3 ECC-R SDRAM Modules Mac Pro Late 2013 Memory Upgrade Kit-Matched Set-ECC Registered OWC ECC Registered Memory Upgrade Kit-ECC Registered and non-Registered memory may not be mixed Compatible with Mac Pro Late 2013 (December, 2013)Model ID:MacPro6,1 (2.7GHz 3.0GHz, 3.5GHz, 3.7GHz) OWC Memory Lifetime Limited Warranty including Advanced Replacement Program <span class="a-text-bold">Size:</span>16GB (16384MB) 240-pin SDRAM DIMM 2048M x 72, Dual Rank ECC Registered Memory Module Data Rate = 1866MHz Module Bandwidth 14.9GB/s CL13 Voltage 1.5V Apple Specified Thermal Sensor