The SuperAir Plenum Collar, PCO-A and Plenum Collar, PCO-B are suitable for most HVAC applications. It provides a transition from a flat surface like a plenum (made from metal, duct board or insulated ...

China Ductwork Duct Outlet Start Plenum Collar At a main duct or plenum, a starting collar is installed for attaching a straight or split fitting for the ducts. Installing a collar is the first step ...

1. Prevents Cracks The most crucial reason airplane windows are round is safety. Round windows provide structural strength and help distribute the weight more evenly, reducing the risk of cracks.