I've been told they also fit 60 - 70's Norton exhaust nuts as well. I paid about $20 for mine which was Norton specific on ebay. Mine is like yours with every 2nd tooth missing so there is more space between the teeth. This could be because the Norton exhaust nut has one double fin that is solid in between so it can be tapped with a hammer without bending. Your tool would not fit on the flange at that spot.
Most methods of removing these flanges exert pressure in one area only or in two areas (pipe wrench). The danger with this is you can easily put the flanged nut out of round which will wear out the threads in the cylinder head -$$$$. Your tool is ideal because it spreads the pressure evenly among the fins. It's worth $20 easily.
