The propeller has a 68mm diameter and generates about 3.2 lb of forward thrust and 2.6 lb of reverse thrust. There are clockwise and counter-clockwise rotating versions. Thanks to the magic of 3D printing, we can build these in small batches without the need for expensive injection molded tooling. We are selling the propellers here for your convenience, but many of you have your own 3D printers and can print the propellers yourself. We are making the 3D files for the propeller open-source and licensed under CC-NC-SA 4.0.