REFILL STICK PACK: 20 unscented cotton sticks for any essential oil to be put on of your preference and used in the Vent Scent Whole Home Air Fresheners LASTS TO YOUR LIKING: Replace the passive diffuser sticks to extend the smell or stop it to try different scents of your own ZONING: Choose the whole area, room, or level of the home you'd like the freshener & place it on the nearest HVAC vent register EASY INSTALL: Simply slide in the stick after dipping in an essential oil and then clip it onto a vent where you'd like the scent dispersed. No hassle of furnace filter openings ADJUSTABLE STRENGTH: Alter the amount of oil and/or twist the device to adjust air flow to the scent Support Small Business: Vent Scent is an American Owned and Operated Company