This Air Wick, air freshener kit contains an Air Wick plug-in device plus one refill. Designed to release scent continuously, the plug-in device can be adjusted according to requirements (low setting for subtle fragrance or small rooms; or higher for the largest of rooms with enticing and elegant aromas.) Containing natural essential oils, the refill lasts for up to 100 days based on 12 hours usage/day on lowest setting.