This is an 85mm ducted fan impeller specifically designed for the 1503 brushless motor (7.4V, 2750KV). Inspired by the aerodynamic optimization of industrial fans, it features seven thin-walled blades and a variable blade pitch that tapers from 25° at the root to 18° at the tip, achieving an optimal balance between airflow volume and noise level under the limited torque of the 1503 motor. The layer height is 0.12mm, and during installation, the impeller is directly secured to the motor housing using two M1.6 countersunk screws through the hub.