2x512MB RAM Memory Upgrade for the Compaq Presario 2100 and US Series Laptops (DDR-266, PC2100, SODIMM) Guaranteed Compatible for the Compaq Presario 2100 Series, 2110US, 2135US, 2140US, 2190US, 2195US, 2210US. If your system isn't on this list, or you are unsure about compatibility, call us! Speed up your system with up to 1.0GB of Memory! Lifetime Replacement Warranty! Will ship the same day when ordered at or before 4pm EST! All others ship next day! Fully-staffed call center to help with installation or inquiries! Call 866-335-1355 with questions or for help!