Wrench hex is 1.750" and inside diameter where it threads on the fitting is 1.320". Nut is in excellent condition and appears to have no wrench marks on it.
Made from billet alum. and anodized for corrosion protection and galling prevention.
Note: This is a used item. This item might have been taken in on a trade. RBS may have inspected this item and deemed re-usable. There is no warranty expressed or implied with this item.