Crafted with precision, these four- fan props feature a sleek design and a 1.5mm central hole, making them ideal for various DIY projects. Their aerodynamic structure ensures efficient airflow, enhancing performance in model aircraft, miniature wind turbines, and other creative applications. practical for hobbyists and science enthusiasts alike. Features -Color:Yellow -Material:Plastic -Size:3.90X3.90X0.80cm/1.53X1.53X0.31in -Precision craftsmanship: crafted with precision, these 1.5 mm hole diameter four fan propellers enhance the intricate details of your handmade models -Stable rotation: the 5 mm hole design ensures stable rotation, significantly improving the power efficiency of your models -Versatile size: with a 40 mm size, these propellers are suitable for various model fan needs, widely used in aviation models and technology education -Aerodynamic design: the four design increases aerodynamic performance and reduces noise, providing for a quiet operating environment -Diy model building: practical for handmade model making, these propellers can be used in the construction of diy airplanes, ships, and other list: 20pcs x micro propeller