These Georgi Mirov "oversquare" props for for F5D pylons with gear drives. These type of props were first seen in Muncie, Indiana at the F5D worlds in 2010. People were amazed that a large diameter prop could make a model go that fast. Much quieter than a "regular" small, high rpm pylon style prop. Super strong spread tow carbon construction, collet type CNC machined hub, these are the ticket! Available in 5mm or 6mm shaft size.