1GB DDR2-533 (PC2-4200) RAM Memory Upgrade for the IBM ThinkPad R50 Series R51e (1844EWU) 1GB DDR2-533 PC2-4200 Non-ECC Unbuffered 200 Pin 1.8V CL=4 Memory 64X8 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