TS-7840 M2 SATA
From embeddedTS Manuals
The m.2 SATA SSD port supports 2242 (22mmx42mm) drives supporting SATA III. The m.2 port includes a B key. This header does not include a pcie lane as used by NVME. If this is programmed with a bootable image this will be preferred over the onboard flash in the boot order.