What is the major differences between this and the Trektop NX?
The NX doesn't fully open, it only has sunrider or safari mode. The Trektop Ultra has advanced sunrider (open above front and rear seats), fully open (folds back into trunk) and safari mode. The ultra also has loft assist mechanisms that make it much easier to open and close, and it comes with all of the hardware (foor surrounds, windshield header, etc)