Full Details from Amazon.com : http://www.amazon.com/gp/product/B005CPU5QW?tag=onigi-20
4 GB Dell New Certified Memory RAM Upgrade for Dell Latitude E6400 / 6400 ATG Laptops SNPNY687C/4G
Dell Certified
Lifetime Warranty
800 MHz PC2-6400 SO DIMM 200-pin