16GB ( 4 X 4GB ) RAM Memory for APPLE MAC PRO 2006 1st Gen 1,1 ( 16 GB DDR2 667MHz ECC FB DIMM) 16GB (4GB X4) DDR2 PC2-5300F 667MHz CL5 ECC REGISTERED 240 PIN DIMMS Built and tested in our ISO 9001 certified facility Dataram, a trusted brand name since 1967 100% compatibility guarantee or full money back Lifetime Warranty