TuffBox is a heavy, 1-piece durable polymer shell. The virtually air-tight molded design delivers 100% of airflow. Using an innovative stepped design supporting 3 duct sizes, collars are 1" & beaded to hold flexible duct in place while securing strap.
MPN: 81966
Features
Stepped Collar for multiple duct sizes
To be used on a 6"x6" square duct to convert to round.