LENOVO 03X3815 COMP 4GB DDR3-1333MHZ ECC 1.5V DR RDIMMAddOn 4GB DDR3 SDRAM Memory Module 4 GB (1 x 4GB) DDR3 1333 PC3 10664 DDR3 SDRAM 1333 MHz Single rank Memory CL9 1. 50 V ECC Registered 240 pin DIMM Lifetime Warranty VPN: 03X3815 AM SKU: RSC724792 UPC: 821455637470 DIMM 4 GB of memory makes a perfect symmetry with your latest model processor and boosts up your computer's performance Up to 1333 MHz memory speed with Registered signal for remarkable multitasking capability 240 pin pin DDR3 SDRAM