Description:4GB 1600MHz DDR3 Non-ECC CL9 DIMM (Kit of 2) XMP
Detailed Specifications:Standard 256M X 64 Non-ECC 1600MHz 240-pin Unbuffered DIMM (DDR3, 1.65V, CL9, FBGA, Gold)  (Datasheet)
Mfgr's System P/N's:N/A
Form Factor:Memory Module
Pieces/Unit:2 (Two 2GB modules, totaling 4GB)