Gravity Ventilators offer the Turbine, Pul-Air and Insul-Air models. Turbines are ideal for the general ventilation of factories, farm and agricultural buildings, commercial and public structures and homes. The Pul-Air is a simple device designed to permit an easy outward flow of air with no internal obstructions or moving parts to require maintenance. The Insul-Air is the ideal choice where an extended airshaft is necessary, to clear the peak of a roof for example. It features all the sturdy construction-details of the Pul-Air plus an extended airshaft and an integral flat mounting base. Click here for more product information: https://www.pennbarry.com/Catalog%20Home/Commercial/Commercial%20Specia…