@bodems I'm not sure between an mSATA or a mini PCIe.
On this page, they mention it as "A slot for expansion cards is also present." (in the middle of the page.
https://www.notebookcheck.net/Review-Acer-Aspire-7551G-Notebook.33866.0.html
Ho, but mSATA and mini PCIe seem to be the same "The connector and form-factors are the same": https://superuser.com/a/838569
What's the difference between mini PCIe and mSATA interfaces and SSDs?

Are they even different at all? I've seen SSDs being sold on the market being tagged with both mSATA and mini PCIe. I've seen marketing ads that say mini PCIe are better than mSATA which suggests ...

Super User