The orifice has a double-jacket construction and seals the outlet from the fireplace flue to the chimney.

Thanks to this, condensates formed as a result of temperature changes in the chimney fly into the inside of the fireplace, where they are heated and changed into steam.

The water that flows from the chimney dripping does not get out of the chimney, without causing corrosion and the illusion of leakage at the fireplace welds.