4GB Upgrade for a Lenovo ThinkPad T400 Series System (DDR3 PC3-8500, NON-ECC, ) 204-pin SODIMM DDR3-1066 DDR3 PC3-8500 Unbuffered, NON-ECC, DDR3-1066, 1.5V, 512Meg x 64 The only brand of memory upgrade available directly from a DRAM manufacturer, tested to meet the most stringent industry specifications Install it yourself in about 15 minutes. The same top-quality memory that the worlds largest computer manufacturers install in the systems they sell