Kingston Hyper X Plug n Play 4 GB (2x2GB Modules) 1866MHz DDR3 Non-ECC CL11 Desktop Memory (KHX1866C11D3P1K2/4G) Two 2GB modules of DDR3 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 Unbuffered 1866MHz CL9 240-pin DIMM type