Slips on over the rear or front posts. Can't fit 6" props unless you put the volt meter on the inside. 5" fit and are shown in pictures. A few files included.. the Moment of Inspiration files, and the stl files. the STL's are marked _25mm, _30mm, _32mm Which corresponds to how tall it is. I didn't make it the full 35mm because of the screw heads and the zip tie I have. Pictures are of the 32mm tall one. I am personally using the 25mm one with a FrSky voltage telemetry sensor and it stays put.