That's what they say on that page alright, but something's wrong somewhere.
- If we multiply 12 x 12 x 11.5 we get 1656 cubic cm (i do anyway). When i convert that into cubic inches, on my handy dandy Windowz calculator/converter, it works out to 101 cubic inches - less than i figured out above.
- Converting the length measurements first to inches:
12 cm = 4.72" and 11.5 cm = 4.53"
Therefore 4.72 x 4.72 x 4.53 = 100.9 cubic inches.

So, my original calculation of 136 cubic inches above was off, and the build volume appears to be 101 cubic inches. Why the manufacturer shows "10608 cm3 [633 in3]" as the build volume is a mystery. It doesn't inspire much confidence. It might be worthwhile emailing them and asking about it. Perhaps we've missed something obvious.