Celina manufactures Ventilation Ducts that are intended for open ceiling applications using mostly straight runs with 90 degree turns. Regularly spaced openings provide even distribution of air along the entire length of the ducting. They can be used as an alternative for non-insulated metal ducts and diffuser systems in traditional heating and ventilating applications. They will not dent, rust, rot or corrode and will never need painting. Being made from lightweight vinyl, Ventilation Ducts are an insignificant roof load.