PNY XLR8 MD4096KD2-800-X4 4GB 2x2GB Dual Channel Kit DDR2 800 MHz CL 4-4-4-12 PC2-6400 Desktop DIMM Memory Module Runs at 800 MHz CL4 with 4-4-4-12 timings at 2.0 volts Deliver all the productivity your PC has to offer with PNY Memory Compatible with PC2-6400 (800 MHz), PC2-5300 (667 MHz), and PC2-4200 (533 MHz) systems Helps prepare your PC for running Windows Vista Easy installation, Free 24-hour Technical Support, and Lifetime Warranty!