Patriot Signature DDR3 4GB PC3-12800 1600MHz 1.35V CL11 SODIMM Memory PSD34G1600L81S PC3-12800 (1600MHz) Data Rate 1.35V Power Requirement Ultrabook Compatible 7.8US Refresh Interval (8192 CY CLES/64MS) Auto and self refresh PCB height: 1181(mil) capability PCB height: 1181(mil) Serial Presence-Detect (SPD) 100% Tested