512MB STICK For Dell Optiplex Series SX280. DIMM DDR2 NON-ECC PC2-3200 400MHz RAM Memory. Genuine A-Tech Brand. 512MB STICK DIMM DDR2 NON-ECC PC2-3200 400MHz RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For Dell Optiplex Series. (See Compatibility List Below)