The DJI 9450 Self-Tightening Propeller Set for Phantom 3 is a set of two 9" propellers for the DJI Phantom 3 Advanced or Professional quadcopter. It features one clockwise (CW) and one counter-clockwise (CCW) rotating prop. Optimized for the Phantom 3, these props features plastic threading-as opposed to metal on earlier 9450 props-producing a more secure hold. Self-tightening design avoids prop becoming loose during operation and potentially flying away 9" Self-Tightening Design One Counter-Clockwise (CCW) Prop One Clockwise (CW) Prop Built-In Threads Allow Self-Tightening Integrated Nut Molded Into Propeller.