19M prop ??

[jasoncooperpcola]

Both props on my 150 Yammies say 19m on the outside prop cup and on the backside (where it seats against the thrust washer) along with the size. But i don't know what the m means either. I will put a picture below of the thrust wahser side. I would say you have a good prop for 49 mph at 5200 rpm.