For Cheerson CX-20, Quanum Nova, and other identical quadcopters. These are the four corners required to create your own landing skids. Precisely measured, printed, and tested. What you do from here is up to you, all the hard stuff is done.You can print off one of each corner if you really want to test them, and attach more ABS with cement or what-not. Or try and extend the design any way you see fit.