IRIS+ features self-tightening, screw-on propellers for easy attachment. This set includes TWO propellers: one clockwise and one counterclockwise.This set includes two IRIS+ propellers:One 9.5 x 4.5 T-Motor multirotor self-tightening counterclockwise propellers (with silver nut)One 9.5 x 4.5 T-Motor multirotor self-tightening clockwise (with black nut)