Mac Pro 2006 & Mac Pro 2007 4GB Kit (2X2GB) DDR2 667Mhz ECC PC2-5300 Fully Buffered Dimm Speed: DDR2 667MHz (PC2-5300) Memory Type: 240 pin, ECC Fully buffered, Dual Rank DIMM Meets Apple electrical and thermal specifications. RoHS Compliant. Warranty: Lifetime