Hey bros, i just picked up some nolv and i wanted to know if its real and how many mg's it is (the person i got it off of is not sure what the mgs are)

They are a aspirin sized pill
white
one side has a big "G" on it
the other side has a split marker
on the top it says "TN" on the bottom it says "20"

any clues? thanks bros
Del