The only brass hose end available with the correct 18 degree seat for Stromberg inlet fittings (original or S-jet). So no leaks and period looks too. Big 9/16″ AF hex cost us more to make, but looks right on the hose. Perfect for 5/16″ ID hose – but 3/8″ ID hose also clamps up great. Also fits 9564K-BIG S-jet (standard on BIG 97 carbs).