We're committed to providing quality products. Keep your home's air clean with this filter for FUNMAS indoor dryer vents. The only replacement filter on the market suitable for FUNMAS indoor dryer vents. Protect your home from dust particles. Improve indoor air quality. We recommend gently vacuuming the polyester filter every 6-12 uses of your dryer. You'll know it's time to replace the polyester filter when it looks "," warped, and worn. With gentle vacuuming, a single polyester filter can last up to 2 months or longer, depending on how often you use your dryer.