Designed for versatility, these fan are compatible with small motors, offering seamless integration into STEM projects and model building activities. Their durable construction ensures use, while the compact size makes them suitable for intricate designs. Ideal for repairing or upgrading miniature fans and scientific models. Features -Color:Yellow -Material:Plastic -Size:3.90X3.90X0.80cm/1.53X1.53X0.31in -Sturdy material: made from sturdy materials, these propellers ensure durability and performance for your models -Enhanced efficiency: the 1.5 mm hole diameter design enhances the efficiency of your model's motor, ensuring smooth and stable operation -Wide application: the 40 mm size makes these propellers suitable for a wide range of models, including aircraft and science projects -Noise reduction: the four design helps in reducing noise, making it practical for models that require a quiet environment -Ideal for diy projects: these propellers are ideal for diy projects, allowing you to build and diy your own model airplanes and boats Package list: 20pcs x micro propeller