In this video Jeff from AirRite walks Matt Risinger through the supply ducts for the HVAC system in a new home they're building. You can see how they seal the inside of the ducts as well as insulate the exterior, creating a fiber-free air stream. They go over the advantages of metal ductwork pipe, including needing less duct gauge due to better airflow, and better ability to clean it out down the road whereas flex can become permanently damaged by trying to clean it. They show how the pipes are wrapped externally with insulation so there's no way fiberglass can get inside. Risinger also demos duct mastic, a water-based low-toxic paste to seal seams between joint, on boots and on Ys so seams are airtight, ensuring air flows where you want it to flow. Check out the video to see the pieces broken down and explained, as well as how it looks post-install.