WEB FilterFresh whole home air freshener attaches to any furnace or air conditioner filter. The secret to a pleasant-smelling house! As the central furnace/AC system runs, your home is filled with a gentle scent. Great for parties, open houses, holidays and to help reduce lingering household odors like smoke, kitchen, bathroom, and pet odors. Safer than candles and FilterFresh lasts longer than aerosol sprays. Scents last for days depending on the size of your home and how much the system is running. These 6" x 6" pads attach instantly to any furnace/AC filter. When your system is running, experience a gentle scent that will last for days. Easily attaches to any air filter. Remember to use Filter Fresh with a clean filter for days of refreshing fragrance! Delivers whole home fragrance.