-Fly designed this rim to have thicker 3mm sidewalls on the bottom edge for strength and dent resistance and thinner 1.5mm sidewalls throughout the top of the sidewall to reduce unneeded weight. The drilled inside wall and vertical support walls have an even thinner 1mm thickness. Rounded sidewall edges help to prevent tire pinch flats on hang ups and flat landings. Weight: 18.6oz. per rim.