Toyota Yaris exhaust two bolt flange connection gasket ?estima lucida back box

Hi bought a back box for my lucida it bolts on to the middle section ,not a push on fit with a clamp,but a two bolt flange,the company said does not come with a gasket as you dont need one with this fit ??? but I still think there has to be ,am I wrong ? if no what type shall I have to get,it bolt flange to flange thanks