X201, I think from about 2010 or 2011. It's a little slow, but with the ssd, 8gb ram (instead of 4) and running Linux Mint, it sure isn't bad for a 10+
GZEELE NEW Memoria RAM del Portello Della Copertura per Lenovo Thinkpad per per IBM X200 X200S X201 X201I X200T X201T 44C9555 44C0841 il MONTAGGIO della porta - AliExpress