HD] Installing RAM on a Lenovo Thinkpad T420 Guide T410 T400 - YouTube
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
CMS 16GB (2X8GB) DDR3 10600 1333MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Lenovo® Thinkpad T420 4177, 4178, 4180, 4236 Series - A13 at Amazon.com
Lenovo ThinkPad T420 14'' PC Laptop Intel i5 Dual Core 2.5GHz 8GB RAM 750GB HDD Windows 10 Professional (Used) - Walmart.com