These are prop savers for the Flexbot based on the Blade Nano QX. Just print them out and pop them on. They only fit one way so it's really easy to get them in place. Only issue so far is that when they crash they loosen up, so you have to push them back into place. But they definitely save your propellers from bending, and keep your Flexbot airborne if you run into a wall or furniture at low speeds. You can print multiple at a time, but I had issues with cool-warping with so much area since I didn't use a raft, so I print them out one at a time. I'm working on another version that will keep in place even after a decent crash, so stay tuned.Took the Flexbot frame 3D model to get the scale correct, then created the Prop Saver model in Cinema4D.