It's sometimes necessary to use a reducer. For example you may have a large powerful fan but only wish to make a small hole in the wall of your building for air to travel in and out. A reducer will help you do this.
Sometimes it may be necessary or useful to have the ability to connect equipment or ducting of different sizes in a given extraction system.
The concentric ducting reducer enables you to do this quickly and effectively. The concentric reducer can be used to both decrease and increase the diameters of ducting, depending on the direction in which it is positioned.