The original SE153 is 650 and of course only has 19 frets. Although I have made many with rosewood, this is the first time I have changed anything else on this model. The measurement at the nut is 50 on this one and on all of the SE 153 copies I make. 640 works very well because of the small body while the extra fret is seen by some to be indispensable for modern music. I have resisted making the extra fret standard just like I don’t usually put a marker on the 7th position but obviously these things can be included for no extra cost at the time of ordering.