This E2000 - E2170 Carbon Fiber Reinforced Folding Propeller Kit from DJI includes two CW propeller blades and a folding propeller adapter. Each of the blades are 21" in diamater and are made of Ultra Carbon Pro, an advanced composite material, that allows for lower rotational inertia in combination with high-strength and stiffness. The adapter is a foldable mechanism that allows you to mount the props to the E2000 motor. The blades and adapter are designed specifically for the E2000 system. Installation hardware is included.