What is the maximum the PC3 Pro can handle of SSD size?

It would appear that both the 2.5" SATA drive slot and the mSATA
drive slot use the same SATA controller chip, thus same drivers. So
it would likely be 144PB, (PetaByte = 1024 terabytes). See ATA-6:

http://en.wikipedia.org/wiki/AT_Attachment#Interface_size_limitations

Of course, the OS may limit the sizes due to partition table or file
system limitations.

Now if you are referring to physical size, the mSATA standard has
that fixed. I don't know the 2.5" SATA drive slot's maximum height.

This is standard size supported by SATA-III interface

Sorry all... I worded the question badly.
And thanks for your response, Arwen.
I was indeed speaking of drive capacity, not physical size.

Gabriel, when you say 'this', what are you referring to?

FitPC3's SATA controller