The 4V dome is exactly half of a sphere. As the frequency goes up (2V, 3V, 4V, etc.), the 'roundness' of the dome increases, as does its overall strength. There are six different sized struts in Frequency 4 domes, and you can find those lengths using our Geodesic Dome Calculator.
The dome itself can be assembled as a more permanent structure using glue or welding, or you can use to provided nuts and bolts so that the dome can be assembled and disassembled over and over.