4GB KIT (4 x 1GB) For Dell Optiplex Series 755 760 960 GX280 GX620 GX960. DIMM DDR2 NON-ECC 800MHz RAM Memory 4GB KIT (4 x 1GB) DIMM DDR2 NON-ECC PC2-6400 800MHz 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)