This is the best so far. At least the speed resistance fans can be flipped and cloned easily. The fib circles are awful for accuracy, changing shape...and setting is also difficult. The ideal tool...a speed resistance fan in a COMPLETE circle with circles that can be adjust manually and by ratio..also a readout for the distances on the arcs if desired...2nd angles that go all the way through the circle and can be set independently right on the chart..or by ratio. Essential tools to me.