This aluminum Duct Increaser/Reducer is an adaptor that allows you to connect 3 in. duct to 4 in. duct.
- Connects 3 in. duct to 4 in. duct quickly, easily
- Ideal for bathroom fan exhaust applications
- Seal joined edges with duct tape for increased efficiency
- Use with 3 in. and 4 in. rachet or worm gear clamps to connect duct (sold separately)