Scent Stone Shell Scent Stone Container Holds air fresheners Can place it anywhere in your car, truck, house, office or boat. Use Scent Stone Shells to maximize fragrance and minimize the possibility of causing any damage to vehicle finishes. The use of this holder for the ( K29 Scent Stone ) air freshener is a safe way to provide maximum fragrance to your vehicle and minimize the possibility of causing damage to any vehicle finishes. Fill this case with the K29 Keystone scented stone. This shell will not diminish any finishes or paint, so you can place it anywhere in your car!