1pc of 4GB PC10600 204PIN SODIMM 1333MHZ DDR3 SDRAM. Genuine CMS brand, CMS is one of the most trusted names in the Computer Memory industry and this product carries a Lifetime Warranty from CMS Maximum Memory: 8 GB Expansion: 2 Sockets COMPATIBLE WITH: ThinkCentre M90z 0800-xxx; 0852-xxx; 0870-xxx; 2471-xxx; 3429-xxx; 3650-xxx; 5205-xxx If 4GB is installed, the recognized memory may be reduced to 3.5GB or less with 32-bit operating system.(depending on system configuration and memory allocation). Maximum configurations require a 64-bit operating system.