Amazon.com: CMS 128GB mSATA 6GB/s Internal SSD Compatible with Lenovo ThinkPad T420 Series - C29 : Electronics
ThinkPad T420 Hard Drive Replacement - iFixit Repair Guide
Notebooks - What's this slot on T420 | bit-tech.net Forums
12.7mm 2nd SATA HDD SSD Hard Drive Bay Caddy for Lenovo Thinkpad T420 T430 W530 T530 - Price history & Review | AliExpress Seller - small pill's store | Alitools.io
Lenovo ThinkPad T420 Business Laptop, Intel Core i7-2nd Gen. CPU, 8GB RAM, 256GB SSD, 14 Display, Windows 10 Pro, Refurbished Laptop