The Crystal Air Automatic Spray contains a smart chip programmed to release far – reaching fresh fragrance at time intervals desired by you. This lets you determine the longevity of the refill. In customizing the use pattern, you can set desired dispensing. When battery is weak or fragrance refill needs replacement, the flashing light sensor gives a blur sluggish output. Dispenser should not be operated with empty fragrance can. The Crystal Air Fragrance Dispenser has an electronic eye that senses bright light or low light. You can set it to only spray in the dark (low light) or during the day (or when lights are normally on). The third option allows you to set it to spray 24 hours per day. The spray is metered out in three adjustable time intervals – 7.5 minutes, 15 minutes, or 30 minutes.