All purpose heavy duty ventilation cap that improves exhaust capacities to overcome turbulent, diagonally flowing air currents found along roofs. Used on any type of building as residential, commerical or industrial roof vent. Eliminates backdrafts when used as a flue cap for gas or oil fired heating equipment. Vent is also known as a Breidert Cap, Gary 1092 Cap, Heater Cap, Zippy Cap, etc and is available in sizes 3" to 24" and in Galvanized, Stainless or Aluminum Metal.