Use this Full Set of Propellers for your YUNEEC Typhoon H Plus drone to provide a fresh set of high quality propellers. The set comes with three "A" propellers and three "B" propellers, which are identified right on the blades. The "A" propellers are designed only to be installed onto the "A" motors and the "B" propellers are designed only to be installed onto the "B" motors, which are identified on each drone arm. They quickly install using the push-button design on each motor. YUNEEC recommends the Typhoon H Plus propellers be replaced after 20 flight hours for best performance and safety.