The Autel Robotics EVO2-AC-PROPS-LN EVO II Low-Noise Propellers, Set of 2 is both durable and shatter resistant in extreme crashes. When operating normally, the willow-shaped design helps reduce resistance, maximize flight efficiency, and most importantly, decreases propeller noise. Each propeller is foldable, making both easy to store inside a drone case or gear bag. Please note that this pair of propellers should not be mixed with standard propellers, the combination can cause unstable flight.