The WIDE-BORE GAUGE PORT has a much larger air passage than Discovery and Maximus ports do. It produces more power when used in those models. It also takes up less space in the tube allowing a little more room for air. The difference in inside diameter compared to the Discovery and Maximus gauge ports is shown in the last photo. It's made of brass with a black oxide coating for extra corrosion resistance. It includes the o-rings plus an extra set. This port has wider, deeper o-ring seats with thicker o-rings than those on the Discovery model. The outside diameter of the o-rings is the same as the thinner ones so it fits the same tube size. Military-grade thread-sealing tape about 3.2 mils (.032") thick should be used to seal the threads, we have that tape listed in full rolls and 36" sections.