Automatic deodorizer dispenser
An automatic deodorizer dispenser is an air freshener designed to release the encapsulated scent at a set time, or under preset conditions. Some fresheners operate by releasing a quick burst of scent every nine minutes, 18 minutes, or 36 minutes so the user does not become too accustomed to the smell.
Source: Wikipedia — Automatic deodorizer dispenser (CC BY-SA 4.0)