A-TECH 4GB KIT (2 x 2GB) For Dell Optiplex 210L 740 GX280 Small Form Factor GX320 GX520 GX620 Ultra Small Form Factor SX280. DIMM DDR2 NON-ECC PC2-4200 533MHz RAM Memory. Genuine Brand. 4GB KIT (2 x 2GB) DIMM DDR2 NON-ECC PC2-4200 533MHz RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For Dell Optiplex. (See Compatibility List Below)