Originally Posted by devilishprune
Is the SG scale on it legit? Or do you need to do some conversion based on the brix value?
No, whoever manufactured those didn't do the Brix-SG conversion correctly. You'll need to read it in Brix and convert yourself.
For example, it says that 20 °Bx is about 1.078 when it's actually ~1.082.
Edit: And like Sigafoos says, you'll need to correct for the alcohol in solution to get an FG using only the refractometer. I've found the correlation that everyone uses to be all but worthless though: Refractometer Estimates of Final Gravity