4 PACK – A scientific break-through in clean air methodology with a light fresh scent. It sponges up unwanted air contaminants. Ultra Odor Kill Solid acts like synthetic char-coal. Its magnetic sponge attracts and deactivates the harmful pollutants in the air. Uncapped containers are placed into the return side of the air conditioner. Ultra Odor Kill Solid will become active after opened, and will be effective while it dissolves for approximately 3 months. This product is packaged in four (4) 8oz containers, and has years of shelf life as long as container is kept closed.