Patented design and only soffit vent built to direct moist bathroom air away from the soffit, not under it. This prevents several issues, including water and roof damage, increased moisture resulting in higher heating and air conditioning costs, and indoor air quality issues that can impact health. Scientifically proven to displace the most amount of exhausted air away from the home (95%+ of moist air). Don't put your family's wellness or the health of your home at risk by using a less effective, cheap soffit vent. Damper/flap provides a closed system that prevents pests and air from entering home. The small front grill openings help increase air speed to push moisture over the soffit edge. Note: Meant for bath fans up to 110 CFM. Higher CFM fans may experience louder fan noise and restricted air flow. Easy to install; easy to clean via removable screen; fits a 4-inch vent hose (4 screws included). Durable resin plastic that's weather resistant; Made in the USA. The PreVent-It under-eave soffit vent effectively directs vented air from bathroom exhaust fans away and prevents it from re-entering your home. The patented design dispels the misconception that soffit vents should discharge air under the soffit. It was scientifically proven in lab testing at a major U.S. university to discharge 95%+ of exhausted air away from the passive soffit zone. Existing soffit vents discharge the majority of moisture directly under soffits. The problem with those designs is that the moist air can end up going under the roof. That can cause unsuspecting roof damage, water damage, increased allergies, higher utility bills, and/or a negative impact on the environment. Use our patented soffit vent to avoid those potential problems and danger to your family’s health and safety. Meant for bath exhaust fans up to 110 CFM using 4 inch duct work.