This 4-inch starting collar features an integrated damper, allowing for precise airflow regulation and improved system efficiency. The collar is specifically designed for easy attachment to ductboard, providing a seamless transition from your ductboard to the round ducting. Ideal for HVAC professionals and DIY enthusiasts, this starting collar with damper is easy to install and fits perfectly with standard ductboard and ducting components. The adjustable damper allows you to control the airflow to specific areas, enhancing comfort and energy efficiency throughout your space.