The best unicycle cranks ! These are the recommanded crank sizes depending on the type of unicycle :
These are just recommanded sizes. The ideal crank size depends on how fast you want to go, and what kind of terrain you're riding (shorter cranks are good for high speed and flatter terrain, and longer cranks work best at short speeds over rougher terrain).
With low-cost steel cranks € 10, you can often afford to have several sizes, to test and progress faster!
Happy Unicycle!