32GB (4 X 8GB) DDR3 PC3-8500R 1066MHz CL7 1.5V 2RX4 240PIN DIMMS. THEASE ARE new MODULES AND ARE GUARANTEED TO WORK WITH ALL  APPLE MAC PRO 4,1 NEHALEM MODELS

***NOTE: The Mac Pro can use either ECC UNBUFFERED or ECC REGISTERED DIMMS, but they cannot be mixed. These are ECC REGISTERED, so remove all UNBUFFERED DIMMS before installing****

This UPGRADE WORKS WITH THE FOLLOWING MODELS

Mac Pro "Quad Core" 2.66 (2009/Nehalem)2.66 GHz Q. Core Xeon W3520

Mac Pro "Quad Core" 2.93 (2009/Nehalem)2.93 GHz Q. Core Xeon W3540

Mac Pro "Quad Core" 3.33 (2009/Nehalem)3.33 GHz Q. Core Xeon W3580

Mac Pro "Eight Core" 2.26 (2009/Nehalem)2.26 GHz Q. Core Xeon E5520 x2

Mac Pro "Eight Core" 2.66 (2009/Nehalem)2.66 GHz Q. Core Xeon X5550 x2

Mac Pro "Eight Core" 2.93 (2009/Nehalem)2.93 GHz Q. Core Xeon X5570 x2

Mac Pro "Quad Core" 2.8 (2010/Nehalem)2.8 GHz Q. Core Xeon W3530

Mac Pro "Quad Core" 3.2 (2010/Nehalem)3.2 GHz Q. Core Xeon W3565

This memory has a lifetime replacement warranty.