This is an interesting variable pitch-sort of constant speed propeller. I have one and I use it rarely but since it starts out at 11 pitch and adds pitch as required, it will really pull. The link shows a little about it. I don't believe they are made any longer. They were marketed by Land and Sea and the price got so high that they were not worth it. They are probably around used because most people became aggravated with them because of the tuning and maintenance required. I would not suggest that it be used every day but it is fun to play with. http://www.land-and-sea.com/marine/torque-shift/torque-shift.htm jim
