I bought a 2,5” SSD for my thinkpad e595 and when I've opened it, theres something in the ssd slot. I bought it just with M.2 memory, so I don't know what
12.7mm 2nd HDD SSD Hard Drive Caddy Tray Replacement for Lenovo Thinkpad T420 T430 T510 T520 T530 W510 W520 W530 - Price history & Review | AliExpress Seller - DEALS PLUS TECHNOLOGY
Amazon.com: 2nd HDD SSD Caddy for Lenovo Thinkpad T510 T520 T530 W530 W520 W510 W700DS W700 W701 T430 T420 T420i Laptop, SATA3 Second Solid State Hard Drive Enclosure, CD DVD Optical Bay
2nd HDD SSD Hard Drive Caddy Tray Replacement for Lenovo Thinkpad T420 T430 T510 T520 T530