Amazon.com: FLEANE 512GB MS02 MicroSata uSATA 1.8inch SSD Compatible with DELL XT1 XT2 IBM X300 X301 T400S T410S Replace MK1229GSG MK1629GSG MK2529GSG 1.8" HDD (512GB) : Electronics
BEWARE: Lenovo Thinkpad L15 Gen3 SSD is practically un-upgradeable. Laptop comes with 256GB and bigger SSD is too thick to fit. There also goes a cooling plate on top. : r/thinkpad