Vent Systems 4" Inch White Straight Inline Duct Coupler – Male-Fit Plastic Ventilation Pipe Fitting for Heating, Cooling & Exhaust Systems – Durable HVAC Straight Pipe Joiner – Indoor Use

Inexpensive. Works well with a 70cfm bathroom fan. The damper included with bathroom fan was garbage. This stops 99% of the backdraft.BTW do not use this on dryer vents. It will plug up with lint and trip the high limit thermal fuse in your dryer. A 7 dollar part that’ll cost you 150-250 dollars to have replaced. Also I would be concerned about the temperature rating of the plastic. It would certainly deform from the heat of the dryer becoming useless.Unit does not have any directional arrows. You have to know what you’re doing to make this work. Horizontal or upflow applications only.

As described and the 4" measurement fit dryer vent hoses I wanted to join. The plastic walls of the item could have been thicker & therefore stronger, but for now it works.

Received as advertised and as scheduled, very light duty with damper blade falling out while installing.

This back flow fitting worked as it should. I combined a dryer vent and bathroom vent together to exit the house. I didn’t want the higher pressure from the dryer to push back into my bathroom.

I was getting cold air back flow from the bathroom vent. I felt cold every time i used the bathroom despite the fact that i have heat. Ever since i connected this simple backdraft damper control, I no longer feel cold when i use the toilet and my plants now survive during the cold winter. I am sure my heating bill got reduced heavily. THANK YOU for this simple device. It was very simple install. Practically and pushed it over the 4 inch PVC pipe sticking out. Didn't use any glue or screws to hold. It naturally fit over the pipe.

The flapper was disconnected, so it arrived technically broken. There description says spring there is no spring in the device, as mentioned in the description. The device could not be mounted vertical as also mentioned in the description. Would avoid this product. Was not satisfied

Came damaged, sent back.

These work as they should and easy to install. So far so good and they are serving their purpose.