Vents TwinFresh Expert RA1-50-2 MERV 8 Filter adds an extra level of particulate filtration to your Twinfresh Expert. Upgrading the internal MERV 5 filter to a MERV 8 significantly improves the air quality by capturing smaller particles and providing a cleaner, healthier environment. This enhanced filtration system is perfect for those looking to reduce allergens, dust, and other airborne pollutants in their home or office.