Product Detail Two 2GB modules, totaling 4GBStandard 256M X 64 Non-ECC 1333MHz 240-pin Unbuffered DIMM (DDR3, 1.5V, CL9, FBGA, Gold) . The "4GB 1333MHz DDR3 Non-ECC CL9 DIMM Kit of 2" is best product for you. We recommended 4GB 1333MHz DDR3 Non-ECC CL9 DIMM Kit of 2