Abstract: A flag mast holder assembly that can accommodate the three most popular trailer hitch ballmount bore diameters BD, namely, 1.0 inch, 0.874 inch and 0.75 inch. Mast holder assembly includes a central bore for receiving the mast of a flag or pennant and is preferably made of aluminum. The mast holder assembly is provided with stainless steel flat washers, lock washer and securing nut. The provision of stainless steel components with the aluminum mast body will be highly resistant to corrosion and oxidation and thus provide an attractive addition to anyone's vehicle. The preferred material is aluminum with stainless components as described above, however, the entire assembly and attaching hardware could be made of nylon, Teflon or suitable non-corrosive plastic materials.