Drobo 8D - SSD Acceleration still mSata?


I just purchased a Drobo 8D which is on the way. I was trying to figure out what drive to purchase for the SSD Acceleration bay, I am pretty sure it should use a mSata drive like other Drobo products - but the Drobo drive selection guide does not list the 8D as being compatible with mSata unlike the 5D3.

Does it use some other kind of drive in the acceleration bay? Just a standard 2.5" internal SSD?