I got this prop on a motor I bought to turn around and sell. I took it to work one night last week and cleaned it up and found the word Michigan and PJ 80 stamped in it. There is nothing else stamped on it. One of the guys at work googled it on his phone and found an ebay ad that said it is a 15P. It is a very big prop with a lot more cup surface than the MW 13 3/4 X 17 I am using now. I am going to put it on my pontoon to get a little more RPM on the WOT. Does anyone have any more data on what kind of prop this might be, cupped, work boat?