Kingston HyperX 4GB (2x2GB) 1066MHz DDR2 Non-ECC CL5 DIMM Desktop Memory 2 X 2GB 1066MHz DDR2 Desktop Memory Utilizes HyperX module with faster latency timing for higher performance and speed Specifically designed and tested for compatibility in various makes and models of desktop computers From the industry leader in PC memory Non-ECC Low-Latency 240-pin unbuffered DIMM type