CMS 16GB (2X8GB) DDR3 10600 1333MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Lenovo® Thinkpad X220 4287, 4290, 4291 Ddr3-1333 - A13 at Amazon.com
16GB KIT (2 x 8GB) for IBM Lenovo ThinkPad X Series X121e X220 Tablet X220i Tablet. SO-DIMM DDR3 Non-ECC PC3-10600 1333MHz RAM Memory. Genuine A-Tech Brand. at Amazon.com
Refurbished: [GRADE-A] Lenovo ThinkPad X220 Business Touch + Pen Tablet Computer - Windows 7 Professional- Core i7-2640M, 250GB HDD, 16GB RAM, 12.5" HD (1366x768) Touch Display - Newegg.com