Deflecto Duct Increaser and Reducer, Plastic Inline Adapter, White, 4” to 3” (IRB43)

As others have said the 4 inch side is the same size as the 4" outlet duct on newer bathroom vent fans BUT I used a hot glue gun to essentially "weld" the two plastic pieces together. To assure a strong connection I wrapped the joint afterward with silicone self adhesive tape. I imagine duct tape would also work. The existing 3" flexible duct was a snug fit, but with a little effort it went over the 3" side of the reducer. I considered using a galvanized steel 3x4 duct adapter (Home Depot, Menards) but because of all the shower moisture being vented out I was concerned with the piece rusting over time. The plastic reducer was cheaper and will be rust-free.

Works very satisfied customer 🙂

Worked as described. Was used to convert a 3in bathroom exhaust to a 4in. Pretty straight forward item.

Fast shipping, Thanks!!

Fits perfect

Tried to adapt bathroom exhaust fan outlet down to existing flex. Unfortunately didn't fit either end as it is the exact same size not allowing to fit inside nor outside.

making good secure connections on venting hose on inboard engines on boats is most important. this plastic adaptor works perfectly Thanks

Part does not work as advertised. 4inch side is to large to slip ducting over tip and to small to the slip over ducting pipe or vent attachment. 3inch side has the same issues.