Celina Industries manufactures ventilation ducts that are intended for simple, open ceiling applications using straight runs with or without 90 degree elbows. The ducts provide even distribution of air the entire length of the run. They can be used as an alternative for uninsulated metal duct and diffuser systems in traditional heating and ventilating applications. They will not dent, rust, rot or corrode, will never need painting and are an insignificant roof load.