4GB [2x2GB] DDR2-667 (PC2-5300) RAM Memory Upgrade Kit for the Lenovo ThinkPad X61s 2GB DDR2-667 PC2-5300 Non-ECC Unbuffered 200 Pin 1.8V CL=5 Memory When you purchase RAM from 4AllDeals, it comes with a lifetime warranty, as well as lifetime telephone technical support from our US-based technicians. PLEASE NOTE* If you do not purchase this module from 4AllDeals direct, you do not get the lifetime warranty or tech support offered in this ad. Put your trust in a company that has been in business for 12 years, not some fly by night seller you won't be able to get ahold of! 100% Guaranteed Compatible for the computer listed in the title of this ad