The Lambro 4 in. exhaust wall vent with floating damper prevents outside elements and air from entering the vent when the clothes dryer or bath fan is not in use. When the clothes dryer or bath fan is in use, the exhaust air pressure pushes up the floating damper. The exhaust air escapes from the vents bottom. When the clothes dryer or bath fan stops, the damper drops back down to keep outside elements from entering the vent. Made of HIPS (high impact polystyrene), the exhaust wall vent mounts easily over an existing 4 in. vent pipe and can be painted.