This top of the line UltraRest has all the features of the UltraRest HD, plus some new features like the eXtreme edge for the die hard hunter! The new modern design and sleek styling of the UltraRest HDX offers eXtreme compatibility, versatility, and even color customizability! If you are the archer that demands nothing but the top of the line, with all the bells and whistles, then the new UltraRest HDX is for you!