My "Z" is for z-twist. That is one of the options you have when you ply your handspun yarn. I have a Lendrum double treadle wheel. I feel lucky because I bought mine during the 25th anniversary of the company and got a walnut wheel. That was the only year it's been offered in walnut. I've spun everything from alpaca to yak on it. I learned to spin on a spindle, a much more modest investment for beginners. I switched right over to the wheel and continue in the endeavor of becoming a better, more technical spinner. I am still at the point where the fiber I am spinning is the boss of me. It seems to decide how finely it wants to be spun.