8GB KIT 2 x 4GB HP Compaq Z Workstation Series Z600 Z620 DIMM DDR3 ECC Registered PC3-10600 1333MHz Single Rank RAM Memory Genuine A-Tech Brand 8GB KIT (2 x 4GB) DIMM DDR3 ECC Registered PC3-10600 1333MHz Single Rank RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For HP-Compaq Z Workstation Series. (See Compatibility List Below)