Shown with the Oasis to show the size, this gadget measures and monitors temperature and humidity in your case. Since the Oasis collapses when it needs to be refilled, the hygrometer is less important than it would be if you use a device which gives no visual cue that it has gone dry. Also can be used in a room when you have a mass of cold air move into your area and aren’t sure how your internal air is being impacted. Prevention is less expensive than crack repairs. Oasis sold separately.