OFFTEK 4GB Replacement Memory RAM Upgrade for IBM-Lenovo ThinkPad T420 (DDR3-10600) Laptop Memory at Amazon.com
16GB KIT (2 x 8GB) for IBM Lenovo ThinkPad T Series T420 T420i T420s T520 T520i. SO-DIMM DDR3 Non-ECC PC3-10600 1333MHz RAM Memory. Genuine A-Tech Brand. at Amazon.com
Lenovo 04W1636 Thinkpad RAM Slot Door Cover for T420 series | eBay