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
Upgrading Ram from 4Gb to 6Gb on Lenovo Thinkpad T420 - YouTube
Lenovo ThinkPad T420 Business Laptop, Intel Core i7-2nd Gen. CPU, 8GB RAM, 256GB SSD, 14 Display, Windows 10 Pro, Refurbished Laptop